A Beginner’s Guide to SQL String Functions 

A Beginner’s Guide to SQL String Functions 

50 mins read440 Views Comment
clickHere
Updated on Oct 3, 2023 12:03 IST

In this article we will explore different functions like LENGTH,CONCAT,SUBSTRING,TRIM Function LTRIM and RTRIMUPPER and LOWER, REPLACE, LPAD and RPAD functions with examples.

2023_03_MicrosoftTeams-image-2.jpg

SQL (Structured Query language) is a tool for managing and manipulating data stored in relational databases. SQL string functions are a set of built-in functions that allow you to manipulate and manipulate character strings within your SQL statements. Understanding how to work with string functions is essential to writing effective SQL queries. 

Table of contents

Various string functions in SQL let you work with string data. A few of the commonly used SQL string functions are: 

  1. CONCAT: This function allows the user to join two or more strings into a single string. 
  2. LENGTH: The length function returns the number of characters in the string. 
  3. SUBSTRING: It allows the user to extract a specified string portion. 
  4. TRIM: This function removes any leading and trailing spaces in a string. 
  5. UPPER: This function helps us to convert a string to UPPERCASE. 
  6. LOWER: This function helps us to convert a string to lowercase. 
  7. REPLACE: This function substitutes a different string for every instance of a given string. 
  8. CHAR_LENGTH: This function provides a string’s total character count. 
  9. INSTR: The position of a given string within another string is returned by this function. 
  10. LEFT, RIGHT, and MID: These functions allow you to extract characters from the left, right, or middle of a string, respectively. 

Keep in mind that depending on the precise SQL dialect you are using, these functions’ specific syntax and behaviour may change. 

In this beginner’s guide, we will explore some of the most commonly used SQL string functions and show you how to use them to solve real-world problems. 

  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • LTRIM and RTRIM: The LTRIM (left trim) and RTRIM (right trim) functions allow you to remove specified characters from a string’s left or right side, respectively. The syntax for these functions is typical: 

LTRIM(string, characters_to_remove)  

For example, the following SQL statement would remove spaces from the left side of the string “Welcome World “: 

 
SELECT LTRIM(" Welcome World ");
Copy code
 
RTRIM(string, characters_to_remove)
Copy code

The following SQL statement would remove spaces from the right side of the string “Welcome World “: 

 
SELECT RTRIM(" Welcome World ");
Copy code
  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • TRIM Function 

The TRIM function removes leading and trailing spaces from a string. This function is particularly useful when working with character data that may have extra spaces, such as user-entered data. 

To use the TRIM function, you pass in the string you want to trim as the argument, and the function will return the trimmed string. For example: 

 
SELECT TRIM(' Welcome, World! ');
Copy code

The output of this query would be “Welcome, World!” which is the result of removing the leading and trailing spaces from the string “Welcome, World! “. 

  • LTRIM and RTRIM: The LTRIM (left trim) and RTRIM (right trim) functions allow you to remove specified characters from a string’s left or right side, respectively. The syntax for these functions is typical: 

LTRIM(string, characters_to_remove)  

For example, the following SQL statement would remove spaces from the left side of the string “Welcome World “: 

 
SELECT LTRIM(" Welcome World ");
Copy code
 
RTRIM(string, characters_to_remove)
Copy code

The following SQL statement would remove spaces from the right side of the string “Welcome World “: 

 
SELECT RTRIM(" Welcome World ");
Copy code
  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • SUBSTRING Function 

The SUBSTRING function is used to extract a portion of a string. This function is particularly useful when extracting a specific string portion, such as a zip code from an address. 

To use the SUBSTRING function, you pass in the string you want to extract from, the starting position of the extract, and the number of characters you want to extract. For example: 

 
SELECT SUBSTRING('Welcome, World!', 9, 5);
Copy code

The output of this query would be “World”, which is the portion of the string “Welcome, World!” starting at position 9 and extending for 5 characters. 

  • TRIM Function 

The TRIM function removes leading and trailing spaces from a string. This function is particularly useful when working with character data that may have extra spaces, such as user-entered data. 

To use the TRIM function, you pass in the string you want to trim as the argument, and the function will return the trimmed string. For example: 

 
SELECT TRIM(' Welcome, World! ');
Copy code

The output of this query would be “Welcome, World!” which is the result of removing the leading and trailing spaces from the string “Welcome, World! “. 

  • LTRIM and RTRIM: The LTRIM (left trim) and RTRIM (right trim) functions allow you to remove specified characters from a string’s left or right side, respectively. The syntax for these functions is typical: 

LTRIM(string, characters_to_remove)  

For example, the following SQL statement would remove spaces from the left side of the string “Welcome World “: 

 
SELECT LTRIM(" Welcome World ");
Copy code
 
RTRIM(string, characters_to_remove)
Copy code

The following SQL statement would remove spaces from the right side of the string “Welcome World “: 

 
SELECT RTRIM(" Welcome World ");
Copy code
  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • CONCAT Function 

The CONCAT function combines two or more strings into a single string. This function is particularly useful when you combine data from multiple columns into a single string, such as creating a full name from a first and last name column. 

To use the CONCAT function, you pass in the strings you want to combine as arguments, and the function will return the combined string. For example: 

 
SELECT CONCAT('Welcome, ', 'World!');
Copy code

The output of this query would be “Welcome, World!” which is the result of combining the two strings “Welcome,” and “World!”. 

  • SUBSTRING Function 

The SUBSTRING function is used to extract a portion of a string. This function is particularly useful when extracting a specific string portion, such as a zip code from an address. 

To use the SUBSTRING function, you pass in the string you want to extract from, the starting position of the extract, and the number of characters you want to extract. For example: 

 
SELECT SUBSTRING('Welcome, World!', 9, 5);
Copy code

The output of this query would be “World”, which is the portion of the string “Welcome, World!” starting at position 9 and extending for 5 characters. 

  • TRIM Function 

The TRIM function removes leading and trailing spaces from a string. This function is particularly useful when working with character data that may have extra spaces, such as user-entered data. 

To use the TRIM function, you pass in the string you want to trim as the argument, and the function will return the trimmed string. For example: 

 
SELECT TRIM(' Welcome, World! ');
Copy code

The output of this query would be “Welcome, World!” which is the result of removing the leading and trailing spaces from the string “Welcome, World! “. 

  • LTRIM and RTRIM: The LTRIM (left trim) and RTRIM (right trim) functions allow you to remove specified characters from a string’s left or right side, respectively. The syntax for these functions is typical: 

LTRIM(string, characters_to_remove)  

For example, the following SQL statement would remove spaces from the left side of the string “Welcome World “: 

 
SELECT LTRIM(" Welcome World ");
Copy code
 
RTRIM(string, characters_to_remove)
Copy code

The following SQL statement would remove spaces from the right side of the string “Welcome World “: 

 
SELECT RTRIM(" Welcome World ");
Copy code
  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

  • LENGTH Function 

The LENGTH function determines the number of characters in a string. This function is particularly useful when working with character data with a fixed length, such as product or zip codes. 

To use the LENGTH function, you pass in a character string as the argument, and the function will return the number of characters in the string. For example: 

 
SELECT LENGTH('Welcome, World!');
Copy code

The output of this query would be 15, which is the number of characters in the string “Welcome, World!”. 

Using Partition By SQL Clause
Using Partition By SQL Clause
The Partition By SQL clause is a subclause of OVER clause that is used in every invocation of window functions such as MAX(), RANK() and AVG().
All About Composite Keys in SQL
All About Composite Keys in SQL
In this article, we will learn about the composite keys in sql, and how to implement them in sql with the help of examples.
INNER JOIN in SQL
INNER JOIN in SQL
SQL JOINS are used to combine more than two or more tables together to extract the useful data from all the tables. In this article, we will discuss INNER JOIN...read more

Must Read: SQL LIMITS

Must Check: SQL Online Course and Certifications

  • CONCAT Function 

The CONCAT function combines two or more strings into a single string. This function is particularly useful when you combine data from multiple columns into a single string, such as creating a full name from a first and last name column. 

To use the CONCAT function, you pass in the strings you want to combine as arguments, and the function will return the combined string. For example: 

 
SELECT CONCAT('Welcome, ', 'World!');
Copy code

The output of this query would be “Welcome, World!” which is the result of combining the two strings “Welcome,” and “World!”. 

  • SUBSTRING Function 

The SUBSTRING function is used to extract a portion of a string. This function is particularly useful when extracting a specific string portion, such as a zip code from an address. 

To use the SUBSTRING function, you pass in the string you want to extract from, the starting position of the extract, and the number of characters you want to extract. For example: 

 
SELECT SUBSTRING('Welcome, World!', 9, 5);
Copy code

The output of this query would be “World”, which is the portion of the string “Welcome, World!” starting at position 9 and extending for 5 characters. 

  • TRIM Function 

The TRIM function removes leading and trailing spaces from a string. This function is particularly useful when working with character data that may have extra spaces, such as user-entered data. 

To use the TRIM function, you pass in the string you want to trim as the argument, and the function will return the trimmed string. For example: 

 
SELECT TRIM(' Welcome, World! ');
Copy code

The output of this query would be “Welcome, World!” which is the result of removing the leading and trailing spaces from the string “Welcome, World! “. 

  • LTRIM and RTRIM: The LTRIM (left trim) and RTRIM (right trim) functions allow you to remove specified characters from a string’s left or right side, respectively. The syntax for these functions is typical: 

LTRIM(string, characters_to_remove)  

For example, the following SQL statement would remove spaces from the left side of the string “Welcome World “: 

 
SELECT LTRIM(" Welcome World ");
Copy code
 
RTRIM(string, characters_to_remove)
Copy code

The following SQL statement would remove spaces from the right side of the string “Welcome World “: 

 
SELECT RTRIM(" Welcome World ");
Copy code
  • UPPER and LOWER Functions 

The UPPER and LOWER functions are used to convert a string to uppercase or lowercase, respectively. These functions are particularly useful when working with case-sensitive data, such as names or email addresses. 

To use the UPPER function, you pass in the string you want to convert to uppercase as the argument, and the function will return the uppercase version of the string. For example: 

 
SELECT UPPER('Welcome, World!');
Copy code

The above query would return “WELCOME, WORLD!”, the uppercase version of the string “Welcome, World!”. 

To use the LOWER function, you pass in the string you want to convert to lowercase as the argument, and the function will return the lowercase version. For example: 

 
SELECT LOWER('Welcome, World!');
Copy code

The output of this query would be “welcome, world!” which is the lowercase version of the string “Welcome, World!”. 

  • REPLACE Function 

The REPLACE function replaces all occurrences of a specified string within a string with another string. This function is particularly useful when you must make multiple replacements within a string, such as replacing all occurrences of a certain word within a sentence. 

To use the REPLACE function, you pass in the string you want to modify, the string you want to replace, and the string you want to replace it with as arguments and the function will return the modified string. For example: 

 
SELECT REPLACE('Welcome, World!', 'World', 'SQL');
Copy code

The output of this query would be “Welcome, SQL!” which is the result of replacing all and any occurrences of the string “World” with the string “SQL” within the string “Welcome, World!”. 

  • INSTR Function 

The INSTR function is used to search for a specified string within another string and return the position of the first occurrence of the specified string. This function is particularly useful when you need to determine the location of a specific string within a larger string, such as the location of a certain word within a sentence. 

To use the INSTR function, you pass in the string you want to search, and the string you want to search for as arguments and the function will return the position of the first occurrence of the specified string. For example: 

 
SELECT INSTR('Welcome, World!', 'World');
Copy code

The output of this query would be 9, which is the position of the first occurrence of the string “World” within the string “Welcome, World!”. 

  • The LEFT, RIGHT, and MID functions allow you to extract characters from a string’s left, right, or middle, respectively. 
  • LEFT: The LEFT function returns a specified number of characters from the beginning of a string. The syntax for this function is typical: 

LEFT(string, number_of_characters) 

For example, the following SQL statement would return the first 7 characters of the string “Welcome World”: 

 
SELECT LEFT("Welcome World", 7);
Copy code

i.e., It would return ‘Welcome.’ 

  • RIGHT: The RIGHT function returns a specified number of characters from the end of a string. The syntax for this function is typical: 

RIGHT(string, number_of_characters) 

For example, the following SQL statement would return the last 5 characters of the string “Welcome World”: 

 
SELECT RIGHT("Welcome World", 5);
Copy code

i.e., It would return ‘World.’ 

  • MID: The MID function returns a specified number of characters from a specified position in a string. The syntax for this function is typical: 

MID(string, start_position, number_of_characters) 

For example, the following SQL statement would return the 3 characters starting from the 3rd position of the string “Welcome World”: 

 
SELECT MID("Welcome World", 3, 3);
Copy code
  • LPAD and RPAD Functions 

The LPAD and RPAD functions are used to pad a string with a specified character to the left or right, respectively. This function is particularly useful when you must ensure that all strings are a specific length, such as when exporting data to a file with a fixed-width format. 

  • To use the LPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT LPAD('Welcome', 10, '*');
Copy code

The output of this query would be “**Welcome”, which is the result of padding the string “Welcome” with the character” to the left until the desired length of 10 characters is reached. 

  • To use the RPAD function, you pass in the string you want to pad, the desired length of the padded string, and the character you want to pad with as arguments and the function will return the padded string. For example: 
 
SELECT RPAD('Welcome', 10, '*');
Copy code
  • STRPOS: The STRPOS function is like the INSTR function, but instead of returning the position of the first occurrence of a substring, it returns the position of the last occurrence. The syntax for this function is typical: 

STRPOS(string, substring) 

For example, the following SQL statement would return the position of the last occurrence of the substring “l” within the string “Welcome World”: 

 
SELECT STRPOS("Welcome World", "l");
Copy code
  • STUFF: The STUFF function allows you to replace a specified string portion with another string. The syntax for this function is typical: 

STUFF(string, start, length, replace_string) 

For example, the following SQL statement would replace the first 7 characters of the string “Welcome World” with the string “Hi”: 

 
SELECT STUFF("Welcome World", 1, 7, "Hi");
Copy code

Those mentioned above are a few of the many string functions available in SQL.  

The same set of functions is available, and the specific syntax for each function can vary depending on your specific SQL dialect. 

Here are some frequently asked questions (FAQs) related to string functions in SQL: 

  1. What is the difference between LENGTH and CHAR_LENGTH functions in SQL?  
  • LENGTH and CHAR_LENGTH functions in SQL have similar functionality and return the same result: the number of characters in a string. However, LENGTH returns the length in bytes, while CHAR_LENGTH returns the length in characters. 
  1. How can I concatenate two or more strings in SQL?  
  • You can concatenate two or more strings in SQL using the ‘CONCAT’ function or the double pipe (||) operator. 
  1. How can I extract a substring from a string in SQL?  
  • You can extract a substring from a string in SQL using the ‘SUBSTRING’ function. 
  1. How can I find the position of a substring within a string in SQL?  
  • You can find the position of a substring within a string in SQL using the ‘LOCATE’ function. 
  1. How can I replace a substring in a string in SQL?  
  • You can replace a substring in a string in SQL using the ‘REPLACE’ function. 
  1. How can I convert a string to upper or lower case in SQL?  
  • You can convert a string to upper or lower case in SQL using the ‘UPPER’ or ‘LOWER’ functions. 
  1. How can I remove leading or trailing spaces from a string in SQL?  
  • You can remove leading or trailing spaces from a string in SQL using the ‘TRIM’ function. 

Conclusion

SQL (Structured Query Language) string functions are used to manipulate and manage character strings within SQL statements. The most commonly used SQL string functions include CONCAT, LENGTH, SUBSTRING, TRIM, UPPER, LOWER, REPLACE, CHAR_LENGTH, INSTR, LEFT, RIGHT, and MID.If you liked this article then like it and share it with your friends.

Contributed by Sai kumar Vongala

About the Author

This is a collection of insightful articles from domain experts in the fields of Cloud Computing, DevOps, AWS, Data Science, Machine Learning, AI, and Natural Language Processing. The range of topics caters to upski... Read Full Bio

Comments