How to fix the Oracle error ORA-01799: a column may not be outer-joined to a subquery?

In this post, you’ll learn more about the Oracle ErrorORA-01799: a column may not be outer-joined to a subquery with the details on why you receive this error and the possible solution to fix it.

Oracle Error Description

ORA-01799: a column may not be outer-joined to a subquery

Reason for the Error ORA-01799: a column may not be outer-joined to a subquery

(+) () is not allowed.

How to fix the Error ORA-01799: a column may not be outer-joined to a subquery ?

You can fix this error in Oracle by following the below steps

Either remove the (+) or make a view out of the subquery. In V6 and before, the (+) was just ignored in this case.