A BETWEEN condition determines whether the value of one expression is in an interval defined by two other expressions.

between_condition::=

All three expressions must be numeric, character, or datetime expressions. In SQL, it is possible that expr1 will be evaluated more than once. If the BETWEEN expression appears in PL/SQL, expr1 is guaranteed to be evaluated only once. If the expressions are not all the same data type, then Oracle Database implicitly converts the expressions to a common data type. If it cannot do so, then it returns an error.

The value of

expr1 NOT BETWEEN expr2 AND expr3

is the value of the expression

NOT (expr1 BETWEEN expr2 AND expr3)

And the value of

expr1 BETWEEN expr2 AND expr3

is the value of the boolean expression:

expr2 <= expr1 AND expr1 <= expr3

If expr3 < expr2, then the interval is empty. If expr1 is NULL, then the result is NULL. If expr1 is not NULL, then the value is FALSE in the ordinary case and TRUE when the keyword NOT is used.

The boolean operator AND may produce unexpected results. Specifically, in the expression x AND y, the condition x IS NULL is not sufficient to determine the value of the expression. The second operand still must be evaluated. The result is FALSE if the second operand has the value FALSE and NULL otherwise. See Logical Conditions for more information on AND.

[NOT] BETWEEN x AND y

SELECT * FROM employees
  WHERE salary
  BETWEEN 2000 AND 3000
  ORDER BY employee_id;