Comparison Conditions

Comparison conditions compare one expression with another. The result of such a comparison can be TRUE, FALSE, or UNKNOWN.

Table 5-2 lists comparison conditions.

Table 5-2   Comparison Conditions

=

SELECT *
  FROM employees
  WHERE salary = 2500;

!=
^=
<   >
¬=

SELECT *
  FROM employees
  WHERE salary != 2500;

>

<

SELECT * FROM employees
  WHERE salary > 2500;
SELECT * FROM employees
  WHERE salary < 2500;

>=

<= 

SELECT * FROM employees
  WHERE salary >= 2500;
SELECT * FROM employees
  WHERE salary <= 2500;

ANY
SOME 

SELECT * FROM employees
  WHERE salary = ANY
  (SELECT salary 
   FROM employees
  WHERE department_id = 30);

ALL 

SELECT * FROM employees
  WHERE salary >=
  ALL ( 1400, 3000);

Simple Comparison Conditions

A simple comparison condition specifies a comparison with expressions or subquery results.

simple_comparison_condition::=

expression_list::=

If you use the lower form of this condition (with multiple expressions to the left of the operator), then you must use the lower form of the expression_list, and the values returned by the subquery must match in number and datatype the expressions in expression_list.

Group Comparison Conditions

A group comparison condition specifies a comparison with any or all members in a list or subquery.

group_comparison_condition::=

expression_list::=

If you use the upper form of this condition (with a single expression to the left of the operator), then you must use the upper form of expression_list. If you use the lower form of this condition (with multiple expressions to the left of the operator), then you must use the lower form of expression_list, and the expressions in each expression_list must match in number and datatype the expressions to the left of the operator.