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SET NOCOUNT (Transact-SQL)

  • Άρθρο

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Warehouse in Microsoft Fabric

Controls whether a message that shows the number of rows affected by a Transact-SQL statement or stored procedure is returned after the result set. This message is an extra result set.

Transact-SQL syntax conventions

Syntax

SET NOCOUNT { ON | OFF }

Remarks

When SET NOCOUNT is ON, the count isn't returned. When SET NOCOUNT is OFF, the count is returned.

The @@ROWCOUNT function is updated even when SET NOCOUNT is ON.

SET NOCOUNT ON prevents the sending of DONEINPROC messages to the client for each statement in a stored procedure. For stored procedures that contain several statements that don't return much actual data, or for procedures that contain Transact-SQL loops, setting SET NOCOUNT to ON can provide a significant performance boost, because network traffic is greatly reduced.

The setting specified by SET NOCOUNT is in effect at execute or run time and not at parse time.

To view the current setting for this setting, run the following query.

DECLARE @NOCOUNT VARCHAR(3) = 'OFF';

IF ((512 & @@OPTIONS) = 512)
    SET @NOCOUNT = 'ON';

SELECT @NOCOUNT AS NOCOUNT;

Permissions

Requires membership in the public role.

Examples

The following example prevents the message about the number of rows affected from being displayed. In the following example, (5 rows affected) is only returned to clients from the first SELECT statement.

USE AdventureWorks2022;
GO

SET NOCOUNT OFF;
GO

-- Display the count message.
SELECT TOP (5) LastName
FROM Person.Person
WHERE LastName LIKE 'A%';
GO

-- SET NOCOUNT to ON to no longer display the count message.
SET NOCOUNT ON;
GO

SELECT TOP (5) LastName
FROM Person.Person
WHERE LastName LIKE 'A%';
GO

-- Reset SET NOCOUNT to OFF
SET NOCOUNT OFF;
GO

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