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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
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Pam Lahoud
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Toc

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

EXECUTE versus sp_executesql

There are times when an application must build a T-SQL statement dynamically before executing it on the server. In order to execute a dynamically-created T-SQL statement, we can use either the EXECUTE command or the sp_executesql stored procedure. The sp_executesql procedure is the preferred method for executing dynamic T-SQL because it allows we to add parameter markers and thus increases the likelihood that SQL Server will be able to reuse the plan and avoid costly query compilations.

Here's a sample script from the AdventureWorks database that builds a dynamic T-SQL statement and executes it via the EXECUTE command:

DECLARE @sql nvarchar(MAX), @JobTitle nvarchar(50) = N'Sales Representative';

SET @sql = 'SELECT e.BusinessEntityID, p.FirstName, p.LastName
FROM HumanResources.Employee AS e
INNER JOIN Person.Person AS p ON p.BusinessEntityID...
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