Hi Thesti
I am assuming you want to work this out in SQL Server and not .NET...
Here is the approach I would take:
Assuming I had TableA and TableB. I want to find out all the records in TableA that aren't in TableB, based on a column RecordId. First step, find out all the records in TableA that ARE in TableB:
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SELECT a.RecordId
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FROM TableA a
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INNER JOIN TableB b
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ON a.RecordId = b.RecordId
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Then, expand the code so that you return the records that AREN'T in this resultset:
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SELECT TableA.*
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FROM TableA
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WHERE TableA.RecordId NOT IN
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(
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SELECT a.RecordId
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FROM TableA a
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INNER JOIN TableB b
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ON a.RecordId = b.RecordId
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)
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This can also be written as a OUTER JOIN with a WHERE TableB.SomeColumn IS NULL. A query written this way will also run faster, but I find it harder to read, so I didn't write it that way.
HTH
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