String Functions

String functions in SQL are used to manipulate character data within queries. They perform operations such as concatenation, substring extraction, case conversion, and trimming. These functions help modify or format string values to meet specific requirements. Common string functions include CONCAT, SUBSTRING, UPPER, LOWER, and TRIM. They enhance the flexibility and functionality of SQL queries when working with textual data.

 

CONCATE: CONCAT is a string function in SQL used to concatenate two or more strings into a single string.

SELECT CONCAT(first_name, ' ', last_name) AS full_name FROM employees;

·  In this example, we're using CONCAT to combine the 'first_name' and 'last_name' columns from the 'employees' table into a single string representing the full name.

·  The 'first_name' and 'last_name' columns are concatenated together with a space (' ') between them.

·  The AS clause is used to alias the concatenated result as 'full_name'.

·  This query returns the full name of each employee as a single string, combining their first and last names.

 

SUBSTRING: is a string function in SQL used to extract a substring from a given string.

SELECT SUBSTRING('Hello World', 1, 5) AS result;

·  SUBSTRING function is used to extract a substring from the string 'Hello World'.

·  The first parameter ('Hello World') is the source string.

·  The second parameter (1) specifies the starting position from where the substring extraction begins.

·  The third parameter (5) specifies the length of the substring to be extracted.

·  The result of this query would be 'Hello', which is the substring extracted from the source string starting from position 1 and having a length of 5 characters.

 

UPPER: is a string function in SQL used to convert a string to uppercase.

SELECT UPPER('hello') AS uppercase_string;

·  The UPPER function is applied to the string 'hello'.

·  It converts all characters in the string to uppercase.

·  The result of this query would be 'HELLO', which is the uppercase version of the input string 'hello'.

 

LOWER: is a string function in SQL used to convert a string to lowercase.

SELECT LOWER('Hello World') AS lowercase_string;

·  The LOWER function is applied to the string 'Hello World'.

·  It converts all characters in the string to lowercase.

·  The result of this query would be 'hello world', which is the lowercase version of the input string 'Hello World'.

 

TRIM: is a string function in SQL used to remove leading and trailing spaces (or other specified characters) from a string.

SELECT TRIM(' Hello World ') AS trimmed_string;

·  The TRIM function is applied to the string ' Hello World '.

·  It removes leading and trailing spaces from the string.

·  The result of this query would be 'Hello World', which is the input string ' Hello World ' with leading and trailing spaces removed.

 

LENGTH: is a string function in SQL used to determine the number of characters in a string.

SELECT LENGTH('Hello World') AS string_length;

·  The LENGTH function is applied to the string 'Hello World'.

·  It calculates the number of characters in the string.

·  The result of this query would be 11, which is the length of the input string 'Hello World'.