if-case-循环语句

Posted 2020-10-28 一条有梦想的咸鱼

IF语句

drop procedure if exists p_hello_world;  
create procedure p_hello_world(in v_id int)  
begin  
    if (v_id > 0) then  
        select ‘> 0‘;  
    elseif (v_id = 0) then  
        select ‘= 0‘;  
    else  
        select ‘< 0‘;  
    end if;  
end;  
call p_hello_world(-9);  

Case语句

drop procedure if exists pro2;
delimiter //
create procedure pro2(in tid int(10))
begin 
    case tid
        when 1 then
            insert into test values(1,‘xjh‘,‘tx‘,‘15268335587‘);
        when 2 then 
            insert into test values(2,‘zjj‘,‘tx‘,‘15268335587‘);
    end case;
end//
delimiter ;

如果case中未处理的参数则会报 Case not found for CASE statement 错误

循环

　　WHILE-DO…END-WHILE循环

delimiter //
create procedure pro2()
begin 
    set  @i = 0;
    while @i<10 do
        insert into test (tid,tname)values(@i,‘批量‘);
        set @i=@i+1;
    end while;
end//
delimiter ;

　　REPEAT...END REPEAT

delimiter //
create procedure pro2()
begin 
    set  @i = 0;
    repeat
        insert into test (tid,tname)values(@i,‘批量‘);
        set @i = @i + 1;
    UNTIL @i< 10 end repeat;
end//
delimiter ;

　　LOOP...END LOOP

delimiter //
create procedure pro2()
begin 
    set  @i = 0;
    loop_pos:loop
        insert into test (tid,tname)values(@i,‘批量‘);
        set @i = @i + 1;
        if @i =2 then
            leave loop_pos;
        end if;
    end loop;
end//
delimiter ;