数据库-mysql储存过程

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。

一：创建存储过程

　　

MariaDB [test2]> delimiter //
MariaDB [test2]> create procedure p1() #创建存储过程
    -> begin select * from a;
    -> end //
Query OK, 0 rows affected (0.00 sec)

MariaDB [test2]> call p1()            #调用存储过程
    -> ;
    -> //
+------+
| name |
+------+
|    1 |
|    2 |
|    3 |
|    4 |
+------+
4 rows in set (0.00 sec)

Query OK, 0 rows affected (0.00 sec)

MariaDB [test2]> 

二：创建存储过程（带参数）

对于存储过程，可以接收参数，其参数有三类：

• 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

delimiter $

MariaDB [test2]> create procedure p2(
    -> 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 ;

set @t1=4;
set @t2=0;
call p2(1,2,@t1,@t2);
select @t1,@t2;

MariaDB [test2]> select @t1,@t2;
+------+------+
| @t1 | @t2 |
+------+------+
| 104 | 4 |
+------+------+
1 row in set (0.01 sec)

 结果集

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

结果集+out

delimiter \
                        create PROCEDURE p1(
                            OUT p_return_code tinyint
                        )
                        BEGIN 
                          DECLARE exit handler for sqlexception 
                          BEGIN 
                            -- ERROR 
                            set p_return_code = 1; 
                            rollback; 
                          END; 
                         
                          DECLARE exit handler for sqlwarning 
                          BEGIN 
                            -- WARNING 
                            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 ;

游标

                  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 ;

动态执行

                  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 ;

三：删除存储过程

drop procedure proc_name;

四：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)

五：pymysql调用存储过程

#!/usr/bin/env python
# -*- coding:utf-8 -*-
import pymysql

conn = pymysql.connect(host='127.0.0.1', port=3306, user='root', passwd='123', 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)