Ayoka, L.L.C. 202 E. Border Street, Ste 334 Arlington, TX 76010 817.210.4042 ayokasystems

Made in USA Software Development Services

Ayoka, L.L.C.202 E. Border Street, Ste 334Arlington, TX 76010817.210.4042www.ayokasystems.com

By Steve Chang

SQL Server Best Practices

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• Local temporary table• On disk, in tempdb• Visible only to the current scope (like a stored procedure)

• Global temporary table• On disk, in tempdb• Visible to all sessions

Temporary Tables


•CREATE TABLE #people ( id INT, name VARCHAR(32) )

•SELECT id, name INTO #people FROM employees

•DROP TABLE #people

Local Temporary Table


•CREATE TABLE ##people ( id INT, name VARCHAR(32) )

•SELECT id, name INTO ##people FROM employees

•DROP TABLE ##people

Global Temporary Table


•In memory•Performs slightly better than local temporary table•Automatically cleared when the procedure or function goes out of scope•In user-defined function, only allow table variables

Table Variables


•DECLARE @people TABLE ( id INT, name VARCHAR(32) )

Table Variables Syntax


•Cannot truncate a table variable•Table variables cannot be altered•Cannot explicitly add an index to a table variable•Cannot drop a table variable when it is no longer necessary•…

Limitations of Table Variables


•Rarely use ##table•Choose between #table and @table

• Depend on performance and reasonable load testing• Small data set result, use @table• Need index, use #table• In most situations, #table makes more sense

•Avoid cursor•Use #table before large tables’ join.•Do not use the SELECT INTO statement to create #table

Conclusion


•ex_tmp_table.sql•ex_no_tmp_table.sql

Code Examples

Location Work Area Month Piece Sum

Month Hours Sum

YTD Piece Sum

YTD Hours Sum

Location 1 WA01 200 50 1500 250

Location 1 WA02 300 60 1400 300

Location 2 WA01 250 55 1600 300

Location 2 WA02 260 80 3000 320

…


Microsoft SQL ServerManagement Studio Tools

•Actual Execution Plan•Client Statistics•Database Engine Tuning Advisor


Actual Execution Plan (1)

•On SQL Server Management Studio’s tool bar


Actual Execution Plan (2)

•According to the result, determine which sql statements are the bottlenecks


Client Statistics (1)

•On SQL Server Management Studio’s tool bar


Client Statistics (2)

•Review the performance

Made in USA Software Development ServicesDatabase Engine Tuning

Advisor (1)•On SQL Server Management Studio’s tool bar


Advisor (2)•Start Analysis


Advisor (3)•Create recommended indexes


Advisor (4)•ex_advisor.sql

Ayoka, L.L.C. 202 E. Border Street, Ste 334 Arlington, TX 76010 817.210.4042 ayokasystems

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