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From "Greg Monroe" <Greg.Mon...@DukeCE.com>
Subject RE: Joins in torque
Date Thu, 19 Jan 2006 18:46:46 GMT
An alternate thought is to just create a view in the
database (MySQL V5 supports them) and then do a 
psuedo table in the XML to generate the required

You probably already know this, but when you're 
doing complex joins like this, pay close attention
to what needs to be indexed.  Without the right
indices, a large join query against a large number
of records can grind your app to a halt. I tend to 
spend some time in a Query Analyzer type tool 
(e.g. MS SQL's Query Analyzer...lol) to optimize 
any complex queries that underlie views.

> -----Original Message-----
> From: Stephan Spiegel [mailto:spiegel@szwo.de] 
> Sent: Thursday, January 19, 2006 11:17 AM
> To: torque-user@db.apache.org
> Subject: Joins in torque
> Hi, (in case this message is double please excuse me)
> I really do not understand what to do, I do not get the 
> expected results!
> Let´s say I have 3 Tables: T1, T2 and T1_2
> T1:
> ID (integer pk)
> value (varchar)
> ...
> T2:
> ID (integer pk)
> value (varchar)
> ...
> T1_2:
> T1_ID (integer fk->T1)
> T2_ID (integer fk->T2)
> As a result, I would like to have a union table showing the 
> values of T1 and T2 in SQL this would be: select T1.value, 
> T2.value from T1, T2, T1_2 where T1.ID = T1_2.T1_ID and T2.ID 
> = T1_2.T2_ID
> if I get more than this (select * ...) would be fine as well.
> So, I have my classes but when I try to use them as written 
> in Peers HowTo
> (doSelectJoin...) or in Criteria HowTo (crit.addJoin(...)) I 
> always get only the values of the T1_2-table
> As a first step, I try just to get the first half (result 
> should show: T1.value, T1_2.T2_ID) so it should correspond to:
> doSelectJoinT1(crit) in T1_2Peer
> or:
> crit.addJoin(T1.ID,T1_2.T1_ID,Criteria.LEFT_JOIN)
> as a result I just get the T1_2 values. I checked the 
> mailing-list-archives, I can´t find a helpful message. Where 
> is my mistake? Could somebody tell me exactly how to add this join?
> (I´m using torque-3.2, MySQL 5, defaultidMethod=native)
> thanks in advance, Stephan
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