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

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 the newline character. 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
|
SQL Server 2000
|
|---|
|
Make the selected text a comment
|
CTRL+K, CTRL+C
|
CTRL+SHIFT+C
|
|
Uncomment the selected text
|
CTRL+K, CTRL+U
|
CTRL+SHIFT+R
|
For more information about keyboard shortcuts, see SQL Server Management Studio Keyboard Shortcuts.
For multiline comments, see /*...*/ (Comment) (Transact-SQL).

Examples
The following example uses the -- commenting characters.
-- Choose the AdventureWorks database.
USE AdventureWorks;
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

See Also