delimiter //CREATE PROCEDURE proc_if ()BEGIN    declare i int default 0;    if i = 1 THEN        SELECT 1;    ELSEIF i = 2 THEN        SELECT 2;    ELSE        SELECT 7;    END IF;END //delimiter ;if条件语句

二 循环语句

delimiter //CREATE PROCEDURE proc_while ()BEGIN    DECLARE num INT ;    SET num = 0 ;    WHILE num < 10 DO        SELECT            num ;        SET num = num + 1 ;    END WHILE ;END //delimiter ;while循环

delimiter //CREATE PROCEDURE proc_repeat ()BEGIN    DECLARE i INT ;    SET i = 0 ;    repeat        select i;        set i = i + 1;        until i >= 5    end repeat;END //delimiter ; repeat循环

BEGIN    declare i int default 0;    loop_label: loop        set i=i+1;        if i<8 then            iterate loop_label;        end if;        if i>=10 then            leave loop_label;        end if;        select i;    end loop loop_label;ENDloop