Re: Re: [LIP] An SQL question about using multiple tables

Sandip Bhattacharya <[email protected]> Thu, 9 Sep 2004 10:16:21 +0530

Newsgroups	gmane.user-groups.linux.delhi.devel,gmane.user-groups.linux.india.programmers
Organization	Puroga Technologies Pvt. Ltd.
Message-ID	<[email protected]>

On Thursday 09 Sep 2004 10:11 am, Pankaj Kaushal wrote:
>
> for example,
> SELECT ... FROM a,b,c,d,e WHERE a.id=b.id AND a.id=c.id AND a.id=d.id
> AND a.id=e.id and then you can do a DISTINCT (a.id) or whatever

There is no c.id, d.id .... there are no primary keys in b,c,d.

Think of A(aid, aname, aaddress) as a table of people. And B a table of 
languages that the person speaks. Assume there is a table 
LANG(langid,langname). Then B has the structure (aid, langid), and for every 
aid, there can be multiple rows in B.

Similarly, C,D are other table of attributes for the persons in A.

The search criteria specifies a particular combination of all attributes, so 
the criteria is definitely an AND.

- Sandip

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Sandip Bhattacharya    *    Puroga Technologies   *     sandip-/[email protected]
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