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Detecting a cartesian product

Posted on 2004-04-16
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Last Modified: 2012-08-14
I am developing a query builder form something similar to TOAD.
When the user selects multiple columns from various tables i need to detect whether the tables can be joined or not. I want this to be done so that i can avoid a cartesian product when the final query is built and run on the server.
Is there a way to detect if two tables would cause a cartesian product / not.
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Question by:vikramrathour
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by:Lowfatspread
ID: 10848409
which database system?

how are you expecting the joins to be specified anyway?

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by:vikramrathour
ID: 10848532
I am using Oracle Database.
The joins will either be specified by the user or i would be picking up the primary keys of both tables and try and equate them.
Thats what i am thinking of right now but can some one tell me a better solution.
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Lowfatspread earned 100 total points
ID: 10848545
in the main your joins will be on a foreign key to primary key basis  
if your dealing with normalised tables....

the simple way to stop catesian product would be to "demand" the join criteria whenever the user starts to
use a column from a new table...

to automatically do it / present some options to the user then you need to query the "system catalog/tables"
to attempt to detect the foreign key relationsships / indexes available and
present them as options....

sorry i'm not an Oracle "Expert"
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by:musdu
musdu earned 100 total points
ID: 10848626
Hi,

you can find primary key-foreign key relations between tables and columns using dba_constraints table.

regards
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