Post on 14-Feb-2016
description
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
Made in USA Software Development Services
• 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
Made in USA Software Development Services
•CREATE TABLE #people ( id INT, name VARCHAR(32) )
•SELECT id, name INTO #people FROM employees
•DROP TABLE #people
Local Temporary Table
Made in USA Software Development Services
•CREATE TABLE ##people ( id INT, name VARCHAR(32) )
•SELECT id, name INTO ##people FROM employees
•DROP TABLE ##people
Global Temporary Table
Made in USA Software Development Services
•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
Made in USA Software Development Services
•DECLARE @people TABLE ( id INT, name VARCHAR(32) )
Table Variables Syntax
Made in USA Software Development Services
•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
Made in USA Software Development Services
•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
Made in USA Software Development Services
•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
…
Made in USA Software Development Services
Microsoft SQL ServerManagement Studio Tools
•Actual Execution Plan•Client Statistics•Database Engine Tuning Advisor
Made in USA Software Development Services
Actual Execution Plan (1)
•On SQL Server Management Studio’s tool bar
Made in USA Software Development Services
Actual Execution Plan (2)
•According to the result, determine which sql statements are the bottlenecks
Made in USA Software Development Services
Client Statistics (1)
•On SQL Server Management Studio’s tool bar
Made in USA Software Development Services
Client Statistics (2)
•Review the performance
Made in USA Software Development ServicesDatabase Engine Tuning
Advisor (1)•On SQL Server Management Studio’s tool bar
Made in USA Software Development ServicesDatabase Engine Tuning
Advisor (2)•Start Analysis
Made in USA Software Development ServicesDatabase Engine Tuning
Advisor (3)•Create recommended indexes
Made in USA Software Development ServicesDatabase Engine Tuning
Advisor (4)•ex_advisor.sql