The conditions illustrated in the previous section are called simple conditions because each involves a single comparison. It is also possible to develop more complex conditions involving two or more conditional expressions. You combine conditions using the logical operators AND, OR, or NOT to connect conditional expressions. When two or more conditions are combined by logical operators, the conditional expression is called a compound condition. For example, you may want a list of departments from the Product Division only with budgets under $20,000.
The form of the compound condition is:
conditional logical conditional logical conditional
expression1 operator expression2 operator expression3
As with simple conditional expressions, the evaluation of a compound
condition is either true or false, with true resulting in retrieval of
a row and false resulting in no retrieval.