Slash Star Comment (Transact-SQL)

 

Updated: June 10, 2016

Indicates user-provided text. The text between the /* and */ is not evaluated by the server.

Applies to: SQL Server (SQL Server 2008 through current version), Azure SQL Database.

Topic link icon Transact-SQL Syntax Conventions

  
/*  
text_of_comment  
*/  

text_of_comment
Is the text of the comment. This is one or more character strings.

Comments can be inserted on a separate line or within a Transact-SQL statement. Multiple-line comments must be indicated by /* and */. A stylistic convention often used for multiple-line comments is to begin the first line with /*, subsequent lines with **, and end with */.

There is no maximum length for comments.

Nested comments are supported. If the /* character pattern occurs anywhere within an existing comment, it is treated as the start of a nested comment and, therefore, requires a closing */ comment mark. If the closing comment mark does not exist, an error is generated.

For example, the following code generates an error.

DECLARE @comment AS varchar(20);  
GO  
/*  
SELECT @comment = '/*';  
*/   
SELECT @@VERSION;  
GO   

To work around this error, make the following change.

DECLARE @comment AS varchar(20);  
GO  
/*  
SELECT @comment = '/*';  
*/ */  
SELECT @@VERSION;  
GO  
  

The following example uses comments to explain what the section of the code is supposed to do.

USE AdventureWorks2012;  
GO  
/*  
This section of the code joins the Person table with the Address table,   
by using the Employee and BusinessEntityAddress tables in the middle to   
get a list of all the employees in the AdventureWorks2012 database   
and their contact information.  
*/  
SELECT p.FirstName, p.LastName, a.AddressLine1, a.AddressLine2, a.City, a.PostalCode  
FROM Person.Person AS p  
JOIN HumanResources.Employee AS e ON p.BusinessEntityID = e.BusinessEntityID   
JOIN Person.BusinessEntityAddress AS ea ON e.BusinessEntityID = ea.BusinessEntityID  
JOIN Person.Address AS a ON ea.AddressID = a.AddressID;  
GO  

-- (Comment) (Transact-SQL)
Control-of-Flow Language (Transact-SQL)

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