WHERE - IN Search
It is checked whether the tested value is present in one of the given set of values. You can use IN instruction to do this.
EXAMPLE:
The checked expression in the IN instruction can be any legal expression, but usually it is a field name as in the above-mentioned examples.
If NULL value is the result of checked expression, IN instruction also returns NULL.
All elements in the given values list should have the same data-type.
With the help of NOT IN instruction you can be sure that data-element is not the member of the given set.
Note. IN instruction does not extend SQL possibilities as it can be expressed as:
X IN ( A, B, C )
fully equivalent:
(X = A) OR (X = B) OR (X = C)
But IN instruction proposes much more effective way of selection condition expression, especially if set contains big amount of elements.
If set contains one element:
CITY IN ( 'New York' )
it can be replaced with the simple comparison:
CITY = 'New York'