Skip to content

Comments 📝

Success

Comments are a way to add notes to your SQL code. They are not executed and are only there for the benefit of the reader.

Note

Comments can go anywhere in your SQL code! 🚀

Comments can be written with -- or /* */

A "comment" in an SQL statement is some text which is ignored when the query is run. It's a way to add notes to your code to help explain what's happening.

There are two ways to write comments in SQL:

  1. Single-line comments using -- which comment out the rest of the line
  2. Multi-line comments using /* */ which comment out everything they enclose

For info, the multi-line comment goes by several different names:

  • "C-style" comment
  • "Block" comment
  • "Slash-star" comment

Writing comments is super easy, for example:

-- This is a title
SELECT *
FROM HumanResources.Department
;

/*
This query won't run

SELECT *
FROM HumanResources.Department
;
*/

Warning

Comments can be helpful for explaining bits of code, but a comment should never excuse bad code! Use them sparingly and only when necessary.

Tip

This is my personal preference, but I'd recommend using the slash-star comments for any "documentation", and the double-dash comments for any (temporary) commented-out code. This is because the double-dash comments are the ones used by most IDEs to "comment out" code, so following this practice makes it easier to distinguish between the two types of comments.

Further reading

Check out the official Microsoft documentation for more information on comments at:

The video version of this content is also available at: