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Slash Star (Block Comment) (Transact-SQL)

  • Artikkeli

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 SQL database in Microsoft Fabric

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

Transact-SQL syntax conventions

Syntax

/*  
text_of_comment  
*/

Arguments

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

Remarks

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

Examples

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

USE AdventureWorks2022;  
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 AdventureWorks2022 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

See Also

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