What is the execution order of the where clause

This article introduces the relevant knowledge of "what is the execution order of where clauses". In the operation of actual cases, many people will encounter such a dilemma, so let the editor lead you to learn how to deal with these situations. I hope you can read it carefully and be able to achieve something!

Look at the code:

The copy code is as follows:

Set statistics io on

Set statistics time on

Go

Set statistics profile on

Go

Use pubs

Select * from authors

Where (au_fname like's%'or au_fname like'a%')

And (state like 'CA' or state like' UT')

And (cast (zip as int) > 90000)

Select * from authors

Where (au_fname like's%'or au_fname like'a%')

And (cast (zip as int) > 90000)

And (state like 'CA' or state like' UT')

Select * from authors

Where (cast (zip as int) > 90000)

And (au_fname like's%'or au_fname like'a%')

And (state like 'CA' or state like' UT')

Purpose: to verify the query order of each condition of the where statement

Environment: SQLServer 2005Express version

Step: display the query plan

The result: without exception, all are unified into this kind of code.

The copy code is as follows:

|-- Clustered Index Scan (OBJECT: ([pubs]. [DBO] .[ auidind] .UPKCL _ auidind]), WHERE: (CONVERT (int, [pubs]. [DBO]. [zip]. 0) > (90000) AND ([pubs] .[ dbo] .[ pubs] .[ au _ fname] like's%'OR [pubs] .[ au _ fname] like'a%') AND ([pubs]. [DBO] .[ state] like 'CA' OR [pubs] .[ state] like' UT')

This is the end of the content of "what is the order in which where clauses are executed". Thank you for your reading. If you want to know more about the industry, you can follow the website, the editor will output more high-quality practical articles for you!