SQL Comments

SQL comments are used to add descriptive notes or explanations to SQL code without affecting the code's functionality. SQL supports two types of comments: single-line comments and multi-line comments.

Single-line comments begin with two hyphens (--) and continue until the end of the line. For example:

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

Multi-line comments begin with /* and end with */. Any text between the opening and closing symbols is treated as a comment. For example:

/*
This is a multi-line comment.
It can span multiple lines and is useful for adding detailed explanations to SQL code.
*/
SELECT * FROM employees;

Comments can be used to make SQL code more readable and maintainable by providing context and explanations for complex or obscure code. They can also be used to temporarily disable parts of SQL code during development or debugging. However, it is important to use comments sparingly and to keep them up-to-date, as outdated or inaccurate comments can be misleading or confusing.