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Posted by jhofmeyr on 11/08/07 16:14
On Nov 8, 3:29 pm, Nick <nachiket.shirwal...@gmail.com> wrote:
> I have have 3 tables TableA, TableB and TableC. TableA holds the keys
> to TableB and TableC. I need a query which will display the details
> from TableB and TableC depending on the key in TableA.
>
> For eg.
>
> TableA - columns {id, relatedkey, recordType} ===recordType will hold
> values like TableB or TableC
> TableB - columns{id, column1}
> TableC - columns{id, column1}
>
> the query should match the related key to the id of TableA or table B
> based on recordType and show the column1 value with the TabelA id so
> output for this should be
>
> id recordType column1
>
> 1 TableB value of TableB column1
> 2 TableC value of TableC column1
>
> Please help.
>
> Cheers
> Nick
Hi Nick,
Try:
SELECT a.id, a.recordType, CASE WHEN b.column1 IS NULL THEN c.column1
ELSE b.column1 END AS column1
FROM TableA a
LEFT OUTER JOIN TableB b
ON b.id = a.relatedkey
AND a.recordType = 'TableB'
LEFT OUTER JOIN TableC c
ON c.id = a.relatedkey
AND a.recordType = 'TableC'
Good luck!
J
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