Ok today we found out a nicely little bug in the code of our system, a clause in the oracle database where it did a not equal to on two fields.

So for example:

FieldA = 1 FieldB = 1

then FieldA <> FieldB = False then FieldA = FieldB = True

FieldA = 1 FieldB = 2

then FieldA <> FieldB = True then FieldA = FieldB = False

FieldA = null FieldB = 2

then FieldA <> FieldB = False then FieldA = FieldB = False

FieldA = 1 FiledB = null

then FieldA <> FieldB = False then FieldA = FieldB = False

FieldA = null FiledB = null

then FieldA <> FieldB = False then FieldA = FieldB = False

So always remember to insert logic for null values especially in Oracle, apparently SQL Server handles this differently.

Just placed this here as a reminder.