DELIMITER //

CREATE PROCEDURE GetCustomerLevel( IN  pCustomerNumber INT,  OUT pCustomerLevel  VARCHAR(20))
BEGIN
    DECLARE credit DECIMAL DEFAULT 0;

    SELECT creditLimit INTO credit
    FROM customers
    WHERE customerNumber = pCustomerNumber;

    IF credit > 50000 THEN
        SET pCustomerLevel = 'PLATINUM';
        
    ELSEIF credit > 10000 AND credit <= 50000 THEN
        SET pCustomerLevel = 'GOLD';
        
    ELSE
        SET pCustomerLevel = 'SILVER';
        
    END IF;
END //

DELIMITER ;

CALL GetCustomerLevel(447, @level); 
SELECT @level As Customer_Type;