Re: Re: [LIP] An SQL question about using multiple tables
Sandip Bhattacharya <[email protected]>
| 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 -- Sandip Bhattacharya * Puroga Technologies * sandip-/[email protected] Work: http://www.puroga.com * Home: http://www.sandipb.net PGP/GPG Signature: 51A4 6C57 4BC6 8C82 6A65 AE78 B1A1 2280 A129 0FF3 Neutrinos have bad breadth.