SQL Comments

In SQL, comments are used to leave notes or explanations inside your queries. These comments are ignored when the query runs.

Single-line comment

Start a line with -- (two hyphens):

-- This is a single-line comment
SELECT * FROM employees;

Multi-line comment

Wrap the comment with /* ... */:

/*
This is a multi-line comment.
It spans multiple lines.
*/
SELECT name FROM employees;

Inline comment

You can also write comments inline, between parts of a query. This is helpful for disabling or explaining parts of a statement:

SELECT name /*, age */ FROM employees;

In this case, the age column is commented out and won't be selected.

---

In our problems, you'll often see comments used to explain what needs to be done. It's a clear way for us to share instructions without affecting how the query runs.