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Re: InstantDB: How to join three or more tables?


Dirk

You can do three way joins in the WHERE clause with InstantDB, but
unfortunately, joins in the FROM clause are limited to only two tables. This
is mainly because I had assumed that the FROM clause would mainly be used
for OUTER joins, and InstantDB currently limits outer joins to just two
tables.

It's *supposed* to generated a slightly friendlier message than "Table not
found: null" to make this clear. I'll have a look at why it doesn't.

Regards

Pete

--

Peter Hearty                         peter.hearty@lutris.com
Lutris Technologies (UK)        http://www.lutris.com
----- Original Message -----
From: "Dirk Jesko" <jesko@iti.CS.Uni-Magdeburg.De>
To: <instantDB@enhydra.org>
Sent: Monday, October 16, 2000 9:13 AM
Subject: InstantDB: How to join three or more tables?


> Hello,
>
> InstantDBs SQL-Syntax allows joins with more than two tables, but
> executing a Query like:
>
> SELECT * FROM (t1 inner join t2 on t1.id=t2.t1id) inner join t3 on
> t2.id=t3.t2id
>
> results in the following SQL-Exception:
>
> java.sql.SQLException: Table not found: null
>
> I tried some other versions, e.g. with alias names for the tables,
> setting the  parenthesis differently, but it does not help.
> Querying the tables without using JOIN, like in:
>
> SELECT * FROM t1, t2, t3 WHERE t1.id=t2.t1id AND t2.id=t3.t2.id
>
> works fine.
>
> What is wrong with the query using the JOIN-Statement?
>
> Thanks,
> Dirk
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