PL SQL Operators Oracle PLSQL Tutorial

The IN operator checks to see if a value is contained in a specified list of values.
A true result is returned if the value is contained in the list;
otherwise, the expression evaluates to false.
The Syntax for IN

the_value [NOT] IN (value1, value2, value3,...)
the_value is the value you are testing, and
value1, value2, value3,... represents a list of comma-delimited values.
ExpressionResult
3 IN (0,1,2,3,)true
'Sun' IN ('Mon','Tue')false
'Sun' IN ('Sat','Sun')true
3 NOT IN (0,1,2,3)false