IF statement in SQL procedures
IF statements can be used to conditionally enter into some logic based on the status of a condition being satisfied.
The IF statement is logically equivalent to a CASE statements with a searched-case-statement-when clause.
The IF statement supports the use of optional ELSE IF clauses and a default ELSE clause. An END IF clause is required to indicate the end of the statement.
Here is an example of procedure that contains an IF statement:
CREATE PROCEDURE UPDATE_SAL (IN empNum CHAR(6),
INOUT rating SMALLINT)
LANGUAGE SQL
BEGIN
IF rating = 1 THEN
UPDATE employee
SET salary = salary * 1.10, bonus = 1000
WHERE empno = empNum;
ELSEIF rating = 2 THEN
UPDATE employee
SET salary = salary * 1.05, bonus = 500
WHERE empno = empNum;
ELSE
UPDATE employee
SET salary = salary * 1.03, bonus = 0
WHERE empno = empNum;
END IF;
END