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Learn T-SQL Querying

You're reading from   Learn T-SQL Querying A guide to developing efficient and elegant T-SQL code

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Product type Paperback
Published in May 2019
Publisher Packt
ISBN-13 9781789348811
Length 484 pages
Edition 1st Edition
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Authors (2):
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Pedro Lopes Pedro Lopes
Author Profile Icon Pedro Lopes
Pedro Lopes
Pam Lahoud Pam Lahoud
Author Profile Icon Pam Lahoud
Pam Lahoud
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Table of Contents (18) Chapters Close

Preface 1. Section 1: Query Processing Fundamentals FREE CHAPTER
2. Anatomy of a Query 3. Understanding Query Processing 4. Mechanics of the Query Optimizer 5. Section 2: Dos and Donts of T-SQL
6. Exploring Query Execution Plans 7. Writing Elegant T-SQL Queries 8. Easily-Identified T-SQL Anti-Patterns 9. Discovering T-SQL Anti-Patterns in Depth 10. Section 3: Assemble Your Query Troubleshooting Toolbox
11. Building Diagnostic Queries Using DMVs and DMFs 12. Building XEvent Profiler Traces 13. Comparative Analysis of Query Plans 14. Tracking Performance History with Query Store 15. Troubleshooting Live Queries 16. Managing Optimizer Changes with the Query Tuning Assistant 17. Other Books You May Enjoy

Avoiding unnecessary overhead with stored procedures

In stored procedures, use the SET NOCOUNT ON notation even when there's a requirement to return current row count during execution, like in the following example:

CREATE OR ALTER PROCEDURE [dbo].[uspStocksPerWorkOrder] @WorkOrderID [int]
AS
BEGIN
SET NOCOUNT ON;
SELECT wo.StockedQty, wor.WorkOrderID
FROM Production.WorkOrder AS wo
LEFT JOIN Production.WorkOrderRouting AS wor ON wo.WorkOrderID = wor.WorkOrderID
WHERE wo.WorkOrderID = @WorkOrderID;
END;

When SET NOCOUNT is ON, the count indicating the number of rows affected by a T-SQL statement is not returned to the application layer, which provides a performance boost.

The @@ROWCOUNT function will still be incremented even with SET NOCOUNT ON.

To put this to a test, we can use the ostress utility and simulate a client application that executes the...

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