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SQL Select JOIN or WHERE clause
Message
De
22/03/2006 11:16:53
 
 
À
21/03/2006 13:54:19
Information générale
Forum:
Visual FoxPro
Catégorie:
Base de données, Tables, Vues, Index et syntaxe SQL
Versions des environnements
Visual FoxPro:
VFP 9 SP1
OS:
Windows XP SP2
Network:
Windows 2003 Server
Database:
MS SQL Server
Divers
Thread ID:
01106086
Message ID:
01106682
Vues:
21
>>>Hi all,
>>>
>>>Can someone advise me the performance of SQL Select 1) vs 2):
>>>
>>>
>>>1) SELECT abc.*,xyz.dfrom,xyz.dto FROM abc LEFT JOIN xyz ;
>>>      ON abc.fld1=xyz.fld1 WHERE dfrom>=20060101 AND dto<=20060131
>>>
>>>2) SELECT abc.*,xyz.dfrom,xyz.dto FROM abc LEFT JOIN xyz ;
>>>     ON abc.fld1=xyz.fld1 AND dfrom>=20060101 AND dto<=20060131
>>>
>>>Will (1) perform faster than (2)?
>>>
>>>If yes, another question is how I can alter the SQL Select in the DBC if the DBC I am having has the (2) expression and I want to write a program to check for all occurences of (2) SQL Select.
>>>
>>>Thanks in advance.
>>
>>they are not equal
>
>Thanks for the reply. Can u elaborate more?
>
>Regards.
SELECT abc.*,xyz.dfrom,xyz.dto FROM abc LEFT JOIN xyz ;
      ON abc.fld1=xyz.fld1 WHERE dfrom>=20060101 AND dto<=20060131

* this is equal to

SELECT abc.*,xyz.dfrom,xyz.dto FROM abc INNER JOIN xyz ;
      ON abc.fld1=xyz.fld1 AND dfrom>=20060101 AND dto<=20060131
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