Re: Need help understanding LEFT JOIN.

Hallo John,

the left join (+) - operator means this side has to be compared (not necessarily equal) to the other side, if the joined table exists. If the joined table does not exist, this part of the sql will not be evaluated.

Hence, if you outer join (left join) a table (or more than one table) all columns of that table(s) have to be used with the (+) - operator. Any usage without (+) will result in an inner join for that column.

Stephan Langer

John Peterson schrieb:

> Hello, Stephan!
>
> Thank you so much for the info! I gave it a try, and it surely appears to
> work! I don't quite understand it, but I'll surely give this a try.
>
> Thanks again! :-)
>
> John Peterson
>
> "Stephan Langer" <slanger_at_dixi-wc.de> wrote in message
> news:3BDD20B7.991A19BF_at_dixi-wc.de...
> > Hallo,
> >
> > you have to "left join" the constants too, like
> >
> > ...
> > where t.Field = 'Primary'
> > and t.ElementId = tColA.ElementId(+)
> > and t.ElementId = tColB.ElementId(+)
> > and t.ElementId = tColC.ElementId(+)
> > -> and tColA.Field(+) = 'ColA'
> > -> and tColB.Field(+) = 'ColB'
> > -> and tColC.Field(+) = 'ColC'
Received on Mon Oct 29 2001 - 09:04:54 CST