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Join tables questions

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siumui
Yak Posting Veteran

54 Posts

Posted - 2012-03-13 : 13:24:04

Hello all.

I have questions with joining multiple tables if anyone can help.

select *
from employee a
Left Join department b
On a.id = b.id
Left Join salary c
On a.id = c.id

My question is about the order of the join ......table a will be joined with table b first. Then the result of the joined from table a and b will then be join with table c, correct?

Please help.
Thanks.

siumui

tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2012-03-13 : 13:30:11

http://blogs.msdn.com/b/conor_cunningham_msft/archive/2009/12/10/conor-vs-does-join-order-matter.aspx

Tara Kizer
Microsoft MVP for Windows Server System - SQL Server
http://weblogs.sqlteam.com/tarad/

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siumui
Yak Posting Veteran

54 Posts

Posted - 2012-03-13 : 14:28:17

Thank you tkizer.

I'm still not clear after reading from the link you provided. Do you know of any other resources that I can look at?

Thanks.

siumui

tkizer
Almighty SQL Goddess

38200 Posts

Posted - 2012-03-13 : 14:38:24

Lots of articles out there on this subject: https://www.google.com/webhp?sourceid=chrome-instant&ix=sea&ie=UTF-8&ion=1#hl=en&output=search&sclient=psy-ab&q=sql%20server%20does%20ordering%20of%20joins%20matter&oq=&aq=&aqi=&aql=&gs_sm=&gs_upl=&gs_l=&pbx=1&fp=e50b7ed8b228eb18&ix=sea&ion=1&bav=on.2,or.r_gc.r_pw.r_cp.r_qf.,cf.osb&biw=1554&bih=877

Tara Kizer
Microsoft MVP for Windows Server System - SQL Server
http://weblogs.sqlteam.com/tarad/

Subscribe to my blog

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