SQL String Function SUBSTRING()

In SQL, the SUBSTRING() function is used to extract a substring from a string. It takes three arguments: the first argument is the string to extract from, the second argument is the starting position of the substring, and the third argument is the length of the substring.

Here is an example of using the SUBSTRING() function:

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

In this example, the SUBSTRING() function is used to extract a substring from the string 'Hello, World!'. The starting position of the substring is 1, and the length of the substring is 5. The resulting substring, 'Hello', is returned as the result of the query.

The SUBSTRING() function can be useful in a variety of situations, such as when working with text data that needs to be parsed or when generating substrings from larger strings.

It's important to note that the starting position of the substring is 1-based, meaning that the first character in the string has a starting position of 1. Also, the length of the substring is optional; if it is omitted, the SUBSTRING() function will return all characters from the starting position to the end of the string. As always, it's important to consult the documentation for your specific database system to ensure that you are using the function correctly.