The IF statement is a control statement that allows you to conditionally execute the first list of SQL statements whose search-condition evaluates to TRUE. If no search-condition evaluates to TRUE, and an ELSE clause exists, the statement-list in the ELSE clause is executed.
Execution resumes at the first statement after the END IF.
IF statement is different from IF expression
Do not confuse the syntax of the IF statement with that of the IF expression.
For information about the IF expression, see IF expressions.
The following procedure illustrates the use of the IF statement:
CREATE PROCEDURE TopCustomer2 (OUT TopCompany CHAR(35), OUT TopValue INT)
BEGIN
DECLARE err_notfound EXCEPTION
FOR SQLSTATE '02000';
DECLARE curThisCust CURSOR FOR
SELECT CompanyName, CAST( sum(SalesOrderItems.Quantity *
Products.UnitPrice) AS INTEGER) VALUE
FROM Customers
LEFT OUTER JOIN SalesOrders
LEFT OUTER JOIN SalesOrderItems
LEFT OUTER JOIN Products
GROUP BY CompanyName;
DECLARE ThisValue INT;
DECLARE ThisCompany CHAR(35);
SET TopValue = 0;
OPEN curThisCust;
CustomerLoop:
LOOP
FETCH NEXT curThisCust
INTO ThisCompany, ThisValue;
IF SQLSTATE = err_notfound THEN
LEAVE CustomerLoop;
END IF;
IF ThisValue > TopValue THEN
SET TopValue = ThisValue;
SET TopCompany = ThisCompany;
END IF;
END LOOP CustomerLoop;
CLOSE curThisCust;
END;