In Operator (SQL Only)
Determines whether the value of an expression is equal to any of several values in a specified list. This operator can only be used within SQL statements .
expr [Not] In (value1, value2, . . .)
The In operator uses the following arguments.
expr Expression identifying the field that contains the data you want to evaluate
value1, value2 Expression or list of expressions against which you want to evaluate expr
If expr is found in the list of values, the In operator returns True; otherwise, it returns False. You can include the Not logical operator to evaluate the opposite condition (that is, whether expr is not in the list of values).
You might use In to determine whether the value of a control is in a set of specified regions. The following example shows how you can tell if an order is shipped to a western region. If the State is WA, CA, or OR, the IIf function returns "West". Otherwise, it returns "Non-West".
Select IIf([State] In ('WA','CA','OR'), "West", "Non-West")
If expr or any of the entries in the list of values is Null, In returns a Null.