Oracle (+) outer join and constant values

Question

I\'m running into an issue with which I can\'t figure out how to correctly configure a join. I\'m using reporting software that utilizes the (+) indicators in the WHERE clause f

Answer 1

Join option 1 will consider only those rows where CHK.CURRENT = 'Y'. Therefore, if the transaction has no check, CHK.CURRENT will be NULL and the row will not be in the result set.

Join option 2 will consider those rows where CHK.CURRENT, if there was a check, is 'Y'. If the transaction has no check, this test will not be applied and the row will be in the result set.

You can see the difference with this comparison:

Select *
FROM TXN,CHK
WHERE
TXN.CHK_ID = CHK.CHK_ID(+)
and TXN.CURRENT = 'Y'
and CHK.CURRENT(+) = 'Y'
MINUS
Select *
FROM TXN,CHK
WHERE
TXN.CHK_ID = CHK.CHK_ID(+)
and TXN.CURRENT = 'Y'
and CHK.CURRENT = 'Y'