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;

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

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;

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;

                    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 ;

                    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 ;

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='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)