[SQL] Related table question

[Ruslan Zasukhin]

on 1/18/04 7:24 AM, Eric Forget at forgete at cafederic.com wrote:

Hi Eric,

> First, thank you very much for the time you took to resolve those issues.
> And that during a weekend!

What is weekend? :-)


> To summarize, I'm planning to use these rules:
> 
> 1) From the master SELECT I never do a FROM Keyword.
> 
> 2) I always write the keyword clauses either:
> 
>   a) For equality:
>           a.RecID in (select ptr from keyword where name = 'Me')
> 
>   b) For inequality:
> 
>           a.RecID not in (select ptr from keyword where name <> 'Me')
> 
> 
> However, I see b) working without understanding it. For me it looks like a
> double negation. Maybe there is something about SQL I don't understand.

This is query of kind:

    WHERE fld IN (v1, v2, v3)

Here you do not see problems?

In your query we use subselect to get LIST of values.

    WHERE fld IN (select ptr FROM T ... )


-- 
Best regards,
Ruslan Zasukhin      [ I feel the need...the need for speed ]
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e-mail: ruslan at paradigmasoft.com
web: http://www.paradigmasoft.com

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