How to Extract a Substring in SQL

Extracting a substring from a string in SQL can be a useful way to get the information you need from your data. Whether you're looking to get the first few characters of a string, or the last few characters, SQL has a handy function that can help you get the job done.

The Solution

The solution is to use the SUBSTRING() function. This function takes three arguments: the string you want to extract from, the starting position of the substring, and the length of the substring. For example, if you wanted to extract the first three characters from the string 'Hello World', you would use the following query:

SELECT SUBSTRING('Hello World', 1, 3);

This query would return the result 'Hel'.

Examples

Let's look at a few examples of how this function can be used. Suppose you have a table called users with the following data:

If you wanted to extract the domain from each email address, you would use the following query:

SELECT SUBSTRING(email, LENGTH(email) - CHARINDEX('@', REVERSE(email)) + 2, LENGTH(email)) FROM users;

This query would return the result 'example.com', 'example.com', and 'example.net', respectively.

Additional Info

The SUBSTRING() function is supported by most major databases, including MySQL, PostgreSQL, and SQL Server. However, the syntax may vary slightly depending on the database you are using. For more information, check out the documentation for your particular database. 🤓