Returns the portion of the first Period expression that exists from the end of the second Period expression when the Period expressions overlap. When the Period expressions overlap but there is no portion of the first Period expression from the end of the second Period expression or if the Period expressions do not overlap, RDIFF returns NULL. If either Period expression is NULL, RDIFF returns NULL.
period_expression RDIFF period_expression
Any expression that evaluates to a Period data type.
The Period expression must be comparable with the other expression. Implicit casting to a Period data type is not supported.