Re: Why is this a cross join?

On Feb 17, 2013, at 9:16, Tim Uckun <timuckun(at)gmail(dot)com> wrote:

> I have a seemingly simple query that returns way too many records.
> Here is the count query
>
> select count(*) from (
> select crm.*
> from sap_crm_sales crm
> inner join model_configurations mc on left(crm.customer_class, 6)
> = left(mc.sap_code,6)
> ) as s
>
> The crm table has about 44K records, the model table has about 1K the
> join produces about 9 million records

Apparently the first 6 characters of those fields are quite common, which gives you a result for every possible combination of the same 6-character value.

Alban Hertroys
--
If you can't see the forest for the trees,
cut the trees and you'll find there is no forest.