Re: Complex Query

kal121,

I fixed it.

Thanks,
Moorthy

In article <8fv5ed$73g$1_at_nnrp1.deja.com>,   kal121_at_my-deja.com wrote:
> I didn't really examine your query in depth, however here is a very
> important rule to know:
>
> To avoid cartesian products, you must have a minimum of n-1 predicate
> clauses in your query, where "n" is the number of tables you are
> joining.
>
> For example, if you have:
>
> SELECT id, name, dept, city FROM
> t1, t2, t3, t4
>
> you need at least three of these:
>
> WHERE t1.id = t2.id
> AND t2.name = t3.name
> AND t3.dept = t4.dept;
>
> I noticed that your query does not meet this rule.
>
> Hope that helps!
>
> In article <8fv4dk$669$1_at_nnrp1.deja.com>,
> medavarm_at_usa.redcross.org wrote:
> > Hi,
> >
> > I got this query:
> >
> > select d.id, d.site, d.spon, d.total_presenting, r.dtype,
 rr.codabarwbn
> > wbnstart,rx.codabarwbn wbnend
> > from drive d, regis r, uniquewbn rr, uniquewbn rx
> > where trunc(d.ddate)='26-APR-00'
> > and d.id = r.drv
> > and r.id = rr.donatkey
> > and (rr.codabarwbn, rx.codabarwbn) in
> > (select min(uniquewbn.codabarwbn), max(uniquewbn.codabarwbn)
> > from regis,uniquewbn
> > where d.id = regis.drv and regis.id = uniquewbn.donatkey)
> > order by d.id
> >
> > and I get these results:
> >
> > ID SITE SPON TOTAL_PRESENTING D WBNSTAR WBNEND
> > ---------- ---------- ---------- ---------------- - ------- -------
> > 14968 1051 852 35 F 89770 F 89801
> > 14968 1051 852 35 F 89770 F 89801
> >
> > Why am I getting duplicate rows?
> > I know there is a join missing but how do I do that.
> > Can somebody modify this query to avoid the duplicate rows.
> >
> > Thank you,
> > Moorthy
> >
> > Sent via Deja.com http://www.deja.com/
> > Before you buy.
> >
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>

Sent via Deja.com http://www.deja.com/
Before you buy. Received on Wed May 17 2000 - 00:00:00 CDT