-- (Comment) (Transact-SQL)
Applies to: 
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
SQL analytics endpoint in Microsoft Fabric
Warehouse in Microsoft Fabric
Indicates user-provided text. Comments can be inserted on a separate line, nested at the end of a Transact-SQL command line, or within a Transact-SQL statement. The server does not evaluate the comment.
Transact-SQL syntax conventions
Syntax
-- text_of_comment
Arguments
text_of_comment
Is the character string that contains the text of the comment.
Remarks
Use two hyphens (--) for single-line or nested comments. Comments inserted with -- are terminated by a new line, which is specified with a carriage return character (U+000A), line feed character (U+000D), or a combination of the two. There is no maximum length for comments. The following table lists the keyboard shortcuts that you can use to comment or uncomment text.
| Action | Standard |
|---|---|
| Make the selected text a comment | CTRL+K, CTRL+C |
| Uncomment the selected text | CTRL+K, CTRL+U |
For more information about keyboard shortcuts, see SQL Server Management Studio Keyboard Shortcuts.
For multiline comments, see Slash Star (Block Comment) (Transact-SQL).
Examples
The following example uses the -- commenting characters.
-- Choose the AdventureWorks2022 database.
USE AdventureWorks2022;
GO
-- Choose all columns and all rows from the Address table.
SELECT *
FROM Person.Address
ORDER BY PostalCode ASC; -- We do not have to specify ASC because
-- that is the default.
GO