MySQL-存储过程procedure

存储过程:是一个SQL语句集合，当主动去调用存储过程时，其中内部的SQL语句会按照逻辑执行。

1.创建存储过程:

-- 创建存储过程
delimiter //
create procedure p1()
BEGIN
    select * from t1;
END//
delimiter ;

-- 执行存储过程
call p1()

存储过程参数:

in:仅用于传入参数用

out:仅用于返回值用

inout:既可以传入又可以当作返回值

 -- 创建存储过程
 delimiter \\
 create procedure p1(
     in i1 int,
     in i2 int,
     inout i3 int,
     out r1 int
 )
 BEGIN
     DECLARE temp1 int;
     DECLARE temp2 int default 0;

     set temp1 = 1;

     set r1 = i1 + i2 + temp1 + temp2;

     set i3 = i3 + 100;

 end\\
 delimiter ;

 -- 执行存储过程
 set @t1 =4;
 set @t2 = 0;
 CALL p1 (1, 2 ,@t1, @t2);
 SELECT @t1,@t2;

示例:有参存储过程

 delimiter //
 create procedure p1()
 begin
 select * from v1;
 end //
 delimiter ;

示例:结果集

 delimiter //
 create procedure p2(
 in n1  int,
 inout n3 int,
 out n2 int,
 )
 begin
     declare temp1 int;
     declare temp2 int default 0;
     select * from v1;
     set n2 = n1 + 100;
     set n3 = n3 + n1 + 100;
 end //
 delimiter;

示例:结果集+Out

 delimiter \ \
 create PROCEDURE p1(OUT p_return_code tinyint)
 BEGIN
     DECLARE exit handler for sqlexception
     BEGIN
         --执行失败
         set p_return_code = 1;
         rollback;
     END;
     DECLARE exit handler for sqlwarning
     BEGIN
         --警示
         set p_return_code = 2;
         rollback;
     END;

     START TRANSACTION;
     DELETE from tb1;
     insert into tb2(name) values('seven');
     COMMIT;
     -- SUCCESS
     set p_return_code = 0;
 END\ \
 delimiter;

示例:事务

                     delimiter //
                     create procedure p3()
                     begin
                         declare ssid int; -- 自定义变量1
                         declare ssname varchar(50); -- 自定义变量2
                         DECLARE done INT DEFAULT FALSE;

                         DECLARE my_cursor CURSOR FOR select sid,sname from student;
                         DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;

                         open my_cursor;
                             xxoo: LOOP
                                 fetch my_cursor into ssid,ssname;
                                 if done then
                                     leave xxoo;
                                 END IF;
                                 insert into teacher(tname) values(ssname);
                             end loop xxoo;
                         close my_cursor;
                     end  //
                     delimter ;

示例:游标

                     delimiter \\
                     CREATE PROCEDURE p4 (
                         in nid int
                     )
                     BEGIN
                         PREPARE prod FROM 'select * from student where sid > ?';
                         EXECUTE prod USING @nid;
                         DEALLOCATE prepare prod;
                     END\\
                     delimiter ;

示例:动态执行SQL

2.删除存储过程:

drop procedure proc_name;

3.执行存储过程

-- 无参数
call proc_name()

-- 有参数，全in
call proc_name(1,2)

-- 有参数，有in，out，inout
set @t1=0;
set @t2=3;
call proc_name(1,2,@t1,@t2)

 #!/usr/bin/env python
 # -*- coding:utf-8 -*-
 import pymysql
 conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='', db='t1')
 cursor = conn.cursor(cursor=pymysql.cursors.DictCursor)
 # 执行存储过程
 cursor.callproc('p1', args=(1, 22, 3, 4))
 # 获取执行完存储的参数
 cursor.execute("select @_p1_0,@_p1_1,@_p1_2,@_p1_3")
 result = cursor.fetchall()
 conn.commit()
 cursor.close()
 conn.close()
 print(result)

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