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From Ali Demir <dem...@yahoo.com>
Subject Re: OUTER JOIN on more than one table
Date Fri, 29 Sep 2006 13:06:50 GMT
Yes, you can join on any column, FK need not be defined.

Get departments (include those that do not have employees or 
managers) and their employees and their managers:

select d.*, e.*, m.* from (department d left outer join employee e on 
e.dept_id=d.id) left outer join employee m on e.mgr_id=m.id

will work if PK and FK are not defined. But you may want to have 
indexes on your join columns for performance.


At 05:55 AM 9/29/2006, you wrote:
>Hi all,
>i am pretty new to Derby so maybe this is a stupid question, but i 
>couldn't find it in the documentation:
>is there a way in Derby to combine OUTER JOINS on one table?
>For example:
>we have a MAIN table and some SUB tables (SUB1, SUB2...) which all 
>contain MAIN's primary key.
>Is it possible to create a select that can see the MAIN table 
>weither or not the SUB tables have records linked to MAIN?

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