How Can I Iterate Over Query Results to Execute a Stored Procedure for Each Row in SQL Server?

Efficiently Processing Query Results with Stored Procedures in SQL Server

This guide demonstrates how to execute a stored procedure for each row returned from a SQL Server query. Imagine you have a stored procedure designed to update user data based on a user ID. This method shows how to apply that procedure to multiple users retrieved from a query.

Using Cursors for Row-by-Row Processing

SQL Server cursors offer a solution for iterating through query results. Here's an example:

DECLARE @field1 INT;
DECLARE @field2 INT;
DECLARE cur CURSOR LOCAL FOR
    SELECT field1, field2 FROM sometable WHERE someotherfield IS NULL;

OPEN cur;

FETCH NEXT FROM cur INTO @field1, @field2;

WHILE @@FETCH_STATUS = 0
BEGIN
    -- Execute your stored procedure for each row
    EXEC uspYourSproc @field1, @field2;
    FETCH NEXT FROM cur INTO @field1, @field2;
END;

CLOSE cur;
DEALLOCATE cur;

Performance Considerations

Cursors, while convenient for row-by-row processing, can be less efficient than set-based operations. For large datasets, consider loading the results into a temporary table first to improve cursor performance. Avoid using cursors whenever possible for optimal performance.

Superior Alternatives: Set-Based Operations

If feasible, restructuring your logic to use a single UPDATE statement instead of a stored procedure loop will significantly enhance performance. Set-based operations are generally far more efficient than row-by-row processing.

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