There is a table full of grouped values like the following
nodeid link_type primary
11 outflowlink 1
11 inflowlink 1
11 outflowlink 2
Primary of 1 indicates a primary water course. Primary of 2 indicates a secondary water course.
Obviously, one of the out flow links is an error, as its primacy value is 2. It is wrong that water flows from a primary water course into a secondary water course.
How can a function can be designed to find and report such errors?
Is the problem that there exists this row:
11 outflowlink 2
But there is no corresponding row:
11 inflowlink 2
So that you need to find all "orphan" rows that don't have a corresponding member with the opposing data field inflowlink or outflowlink where the "primary" column is the join field between the two rows?