Level Extreme platform
Subscription
Corporate profile
Products & Services
Support
Legal
Français
Need help with simple SELECT - SQL command
Message
From
08/02/2002 13:39:44
 
General information
Forum:
Visual FoxPro
Category:
Coding, syntax & commands
Miscellaneous
Thread ID:
00617474
Message ID:
00617577
Views:
30
>
SELECT state FROM table2 ;
>  WHERE State NOT IN (SELECT state FROM table1)
>* or using correlated query
>SELECT state FROM table2 ;
>  WHERE NOT EXISTS (SELECT state FROM table1 WHERE state = table2.state )
>
>
While VFP might optimize a correlated subquery like yours, in generally, when you can write a readable query without a correlated subquery, it's a better choice. (To the best of my knowledge, any correlated EXISTS query can be rewritten as an IN query, but sometimes the result is pretty obscure.)

Tamar
Previous
Next
Reply
Map
View

Click here to load this message in the networking platform