Comparison Conditions

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

Large objects (LOBs) are not supported in comparison conditions. However, you can use PL/SQL programs for comparisons on CLOB data.

When comparing numeric expressions, Oracle uses numeric precedence to determine whether the condition compares NUMBER, BINARY_FLOAT, or BINARY_DOUBLE values. Please refer to "Numeric Precedence " for information on numeric precedence.

Two objects of nonscalar type are comparable if they are of the same named type and there is a one-to-one correspondence between their elements. In addition, nested tables of user-defined object types, even if their elements are comparable, must have MAP methods defined on them to be used in equality or IN conditions.

See Also: map_order_func_declaration for more information on MAP methods PL/SQL User's Guide and Reference for the requirements for comparing user-defined object types in PL/SQL

Table 6-2 lists comparison conditions.

Table 6-2 Comparison Conditions

Type of Condition	Purpose	Example
=	Equality test.	SELECT * FROM employees WHERE salary = 2500;
!= ^= < > ¬=	Inequality test. Some forms of the inequality condition may be unavailable on some platforms.	SELECT * FROM employees WHERE salary != 2500;
> <	Greater-than and less-than tests.	SELECT * FROM employees WHERE salary > 2500; SELECT * FROM employees WHERE salary < 2500;
>= <=	Greater-than-or-equal-to and less-than-or-equal-to tests.	SELECT * FROM employees WHERE salary >= 2500; SELECT * FROM employees WHERE salary <= 2500;
ANY SOME	Compares a value to each value in a list or returned by a query. Must be preceded by =, !=, >, <, <=, >=. Can be followed by any expression or subquery that returns one or more values. Evaluates to FALSE if the query returns no rows.	SELECT * FROM employees WHERE salary = ANY (SELECT salary FROM employees WHERE department_id = 30);
ALL	Compares a value to every value in a list or returned by a query. Must be preceded by =, !=, >, <, <=, >=. Can be followed by any expression or subquery that returns one or more values. Evaluates to TRUE if the query returns no rows.	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::=

Description of the illustration simple_comparison_condition.gif


expression_list::=

Description of the illustration expression_list.gif

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.

See Also: "Expression Lists " for more information about combining expressions and SELECT for information about subqueries

Group Comparison Conditions

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

group_comparison_condition::=

Description of the illustration group_comparison_condition.gif


expression_list::=

Description of the illustration expression_list.gif

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.

See Also: "Expression Lists " SELECT