The comparison predicate is used to compare two values. The left hand side operand has to be a value expression whereas the right hand sight operand can additionally be a dynamic parameter specification or a scalar sub-query.
<comparison predicate> ::= |
The data types of the two <value expression>s in the <comparison predicate> must be comparable.
If either of the <value expression>s is NULL, the result of the <comparison predicate> is unknown.
It is not possible to test for NULL values with a comparison predicate. You may wish to use a null predicate instead.
More information about comparable types: Open SQL Data Types
SELECT * FROM a WHERE c > 0 |
Comparison predicate.This SELECT yields all rows from table a where the column a.c has a value larger than 0.
DELETE FROM employees WHERE employee_id = ? |
Dynamic Parameter in Comparison Predicate. All employees with the employee_id equal to a given parameter are delete from the table employees.