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SharkD wrote:
> There are three types of joins.
There's one kind of join in relational theory. There are three or four kinds
of joins in SQL, each of which is a join followed by a select.
I.e., inner join isn't like an intersection. It's a cartesian join, followed
by a select where the key from the first table matches the key from the
second table in the result.
Outer joins are peversities caused by people not normalizing columns that
can have NULL in them. If none of your tables can have a NULL, you never
need an outer join.
If it was an intersection, you'd never get any rows, because you wouldn't
have two tables with identical rows in them.
--
Darren New, San Diego CA, USA (PST)
I ordered stamps from Zazzle that read "Place Stamp Here".
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