DROP PROCEDURE IF EXISTS variable_demo;delimiter //   CREATE PROCEDURE variable_demo()BEGINselect 'hello world!'; END;//delimiter ;DROP PROCEDURE IF EXISTS demo1;delimiter //   CREATE PROCEDURE demo1(IN type int)BEGIN    DECLARE c varchar(500);    IF type = 0 THEN        set c = 'param is 0';    ELSEIF type = 1 THEN        set c = 'param is 1';    ELSE        set c = 'param is others, not 0 or 1';    END IF;    select c;END;//delimiter ;DROP PROCEDURE IF EXISTS demo2;delimiter //   CREATE PROCEDURE demo2(IN type int)BEGIN    DECLARE c varchar(500);    CASE type    WHEN 0 THEN        set c = 'param is 0';    WHEN 1 THEN        set c = 'param is 1';    ELSE        set c = 'param is others, not 0 or 1';    END CASE;    select c;END;//delimiter ;DROP PROCEDURE IF EXISTS demo3;delimiter //   CREATE PROCEDURE demo3()BEGIN    declare type int;    DECLARE c varchar(500);    declare i int;    set i=0;    while i<10 do        IF i = 0 THEN        set c = 'param is 0';    ELSEIF i = 1 THEN        set c = 'param is 1';    ELSE        set c = 'param is others, not 0 or 1';    END IF;    select c;    set i=i+1;    end while;END;//delimiter ;//sql语句的操作DROP PROCEDURE IF EXISTS demo4;delimiter //create PROCEDURE  demo4()begindeclare cnt int;select count(*) into cnt from user_order_detail_1;select cnt;end; //delimiter ;DROP PROCEDURE IF EXISTS demo5;delimiter //create PROCEDURE  demo5()begindeclare cnt int;while select count(*) into cnt from user_order_detail_1 doend loop;select cnt;end; //delimiter ;