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SQL Basics

SQL Comments

SQL Comment Syntax

SQL comments use -- for single-line or /* */ for multi-line annotations.

Introduction to SQL Comments

Comments in SQL are used to add notes or explanations within your SQL code. They help increase the readability of your code by providing context to complex queries or sections of code. SQL comments are ignored during execution and are intended for developers or anyone who reads the code.

Single-Line Comments

Single-line comments in SQL are initiated using the -- syntax. Everything following these two dashes on the same line is treated as a comment and is ignored by the SQL engine.

In the above example, the comment -- This query selects all columns from the Customers table provides a brief description of what the SQL statement does.

Multi-Line Comments

For longer explanations or to comment out multiple lines, SQL supports multi-line comments. These comments start with /* and end with */. Everything between these markers is treated as a comment.

Multi-line comments are especially useful for explaining complex query logic or when you want to temporarily disable a block of code without deleting it.

Best Practices for Using Comments

  • Be Concise: Keep your comments brief and to the point.
  • Be Clear: Ensure that your comments clearly describe the purpose or logic of the code they annotate.
  • Keep Updated: Regularly update comments to match the code, preventing them from becoming misleading or outdated.
  • Avoid Obvious Comments: Do not comment on obvious code that is self-explanatory.

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