mysql存储过程开荒

procedure if exists t1; create procedure t1(in a int,in b int,out d varchar(30)) begin declare c int; if a is null then set a = 0; end if; if b is null then set b = 0; end if; set c = a + b; /* select c as sum;*/ select ‘s‘ into d; select d as ‘哈哈‘; -- 输出一列 end; /*调用存储过程*/ set @p_in = 1; call t1(10,1,@p_in);

---

上面我们使用if then条件判断，下面来看使用case when来完成更多的条件：

drop procedure if exists t1;
create procedure t1(in a int,in b int,out c varchar(30))
begin
    declare d int;
    set d = a+1;
    case d
        when 1 then insert into student values(null,‘dx‘,11,now());
        when 2 then insert into student values(null,‘aa‘,11,now());
        else insert into student values(null,‘bb‘,11,now());
    end case;
    select * from student;
end;

---

再来看两个循环，一个是while do循环，一个是loop循环：

/*使用while do循环*/
create procedure t1()
begin
    declare i int DEFAULT 0;
    while i<5 DO    
        insert into student(name) values(i);
        set i=i+1;
    end while;
    select * from student;
end;

/*使用loop循环*/
drop procedure if exists t1;
create procedure t1()
begin
    declare i int DEFAULT 0;
    loop_label:LOOP 
        if i = 3 THEN       
            set i = i + 1;
            ITERATE loop_label;    -- iterate相当于java循环里的continue
        end if;
        insert into student values(null,i,i,now());
        set i = i + 1;
        if i >= 5 THEN      
            leave loop_label;
        end if;
    end loop;
    select * from student;
end;

---

还有比较常用的模糊查询：

/*模糊查询*/
drop procedure if exists t1;
create procedure t1(in a varchar(30),out c varchar(30))
begin
    declare d int;
        select * from student where name like concat(‘%‘,a,‘%‘);

end;

这个例子中要注意的是使用了concat拼接字符串函数。

版权声明：本文为博主原创文章，未经博主允许不得转载。

mysql存储过程开荒

标签：存储过程