SUBSTR in PostgreSQL

In PostgreSQL, the equivalent function to SUBSTR() is also SUBSTRING(). The SUBSTRING() function is used to extract a substring from a string based on a specified starting position and length.

Here's the syntax for the SUBSTRING() function in PostgreSQL:

SUBSTRING(string FROM start FOR length)

- string: The string from which the substring will be extracted.

- start: The starting position from which to extract the substring. It is 1-based (the first character in the string has a position of 1).

- length: The length of the substring to extract.

Let's see an example to illustrate how to use the SUBSTRING() function in PostgreSQL:

Suppose we have a string 'Hello, World!' and we want to extract a substring starting from the 7th position and extending to the end of the string:

SELECT SUBSTRING('Hello, World!' FROM 7) AS extracted_string;

This query will return 'World!' as the extracted substring.

Now, let's say we want to extract only the first 5 characters from the string:

SELECT SUBSTRING('Hello, World!' FROM 1 FOR 5) AS extracted_string;

This query will return 'Hello' as the extracted substring.

So, the SUBSTRING() function in PostgreSQL allows you to extract substrings from strings based on specified starting positions and lengths.