my sql存储过程 基本使用

Posted 2020-10-25 ly77461

--------------创建不带参数的存储过程-----------------
DELIMITER;;
drop PROCEDURE if EXISTS selectStudent;

create PROCEDURE ‘selectStudent‘()
BEGIN
select*from student;
end;;
DELIMITER;


--------------带参数的存储过程--------------------
drop PROCEDURE if EXISTS selectCity;

create PROCEDURE ‘selectCity‘(
in _cityID varchar(10)--输入参数--
)
BEGIN
select *from student where cityID=_cityID;
end;


--------------带有输出参数的存储过程--------------------
drop PROCEDURE if EXISTS selectCity_Name;
CREATE PROCEDURE ‘selectCity_Name‘(
  in _CityID varchar(10)--输入参数,
  out _City varchar(10) --输出参数,
  inout _CityIDName varchar(10) --输入输出参数
)
BEGIN
select*from student where cityID=_CityID and CityName=_CityName INTO _City;
end;

set @_CityID=‘1‘;
set @_CityIDName=‘郑州‘;
call selectCity_Name(@_CityID,@_City,@_CityIDName);
select @_CityIDName as ID,@_City;



-----------带有通配符的存储过程------------
drop PROCEDURE if EXISTS selectCityLike;
create PROCEDURE ‘selectCityLike‘(
in _CityName varchar(10)
)
BEGIN 

set @exec_sql =CONCAT("select *from student where name like ‘%",_CityName,"%‘");
PREPARE stmt from @exec_sql ;  --定义
EXECUTE stmt;--执行预处理语句
DEALLOCATE PREPARE stmt;--删除定义

end



-------循环语句：操作前检查结果----------
create PROCEDURE proc4()
BEGIN

declare var int;
set var=0;

WHILE var<6 DO
insert into t VALUES(var);
set var=var+1;
end while;

end


----------循环语句：操作后检查结果------------
create PROCEDURE proc5()
BEGIN

DECLARE v int;
set v=0;

REPEAT
insert into t VALUES(v);
set v=v+1;
UNTIL v>=5
end repeat;

end



----------循环语句：loop..endloop------------
create PROCEDURE proc6()
BEGIN

declare v int;
set v=0;

loop_lable:LOOP
insert into values(v);

set v=v+1;
if v>=5 THEN
LEAVE loop_lable;
end if;

end loop;

end


----------循环语句：loop..endloop-------------
create PROCEDURE proc7()
BEGIN
DECLARE v int;
set v=0;

loop_lable:LOOP

if v=3 THEN
set v=v+1;
  ITERATE loop_lable;--继续循环
end if;

insert into t values(v);
set v=v+1;
  if v>=5 THEN
    leave loop_lable;--跳出循环
  end if;

end loop;

end;

 

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