python 导出mysql 视图_Python9-MySQL-MySQL存储过程-视图-触发器-函数-day45
视图：某个查询语句设置别名，日后方便使用
CREATE VIEW v1 as SELECT * FROM student WHERE sid >10
-创建：
create view 视图名称 as SQL
视图是虚拟的
-修改
alter view 视图名称 as SQL
-删除
drop view 视图名称
触发器：当对某张表做：增删改操作的时候，可以使用触发器自定义关联行为#插入前
CREATE TRIGGER tri_before_insert_tb1 BEFORE INSERT ON tb1 FOR EACH ROW
BEGIN
...
END#插入后
CREATE TRIGGER tri_after_insert_tb1 AFTER INSERT ON tb1 FOR EACH ROW
BEGIN
...
END#删除前
CREATE TRIGGER tri_before_delete_tb1 BEFORE DELETE ON tb1 FOR EACH ROW
BEGIN
...
END#删除后
CREATE TRIGGER tri_after_delete_tb1 AFTER DELETE ON tb1 FOR EACH ROW
BEGIN
...
END#更新前
CREATE TRIGGER tri_before_update_tb1 BEFORE UPDATE ON tb1 FOR EACH ROW
BEGIN
...
END#更新后
CREATE TRIGGER tri_after_update_tb1 AFTER UPDATE ON tb1 FOR EACH ROW
BEGIN
...
END
delimiter//create TRIGGER t1 BEFORE INSERT on studentforeach ROW
BEGIN
INSERT into teacher(tname) VALUES('tim');
END//delimiter ;--INSERT INTO student(gender,class_id,sname) VALUES('女',2,'多长');#NEW 代指新数据，在两张表中插入同样的数据#OLD 代指老数据 在两张表中删除和更新同样的数据
-- delimiter //
-- create TRIGGER t1 BEFORE INSERT on student foreach ROW--BEGIN--INSERT into teacher(tname) VALUES(NEW.sname);-- END //
-- delimiter ;
内置函数：
执行函数-- SELECT CURDATE() #日期
-- SELECT CHAR_LENGTH('st') #字符串长度
-- SELECT CONCAT('tim','ttutu','ssl') #拼接
时间格式化：
SELECT DATE_FORMAT(date,format)
SELECT DATE_FORMAT('2009-10-04', '%W %M %Y');
自定义函数：
delimiter \\
create function f1(
i1 int,
i2 int)
returns int
BEGIN
declare num int;
set num= i1 +i2;return(num);
END \\
delimiter ;
# 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。
# 保存在MySQL上的一个别名---》一坨SQL语句
方式一：
Mysql：存储过程
程序：调用存储过程
方式二：
mysql：
程序：sql语句
方式三：
mysql
程序：类和对象(sql语句)
delimiter //CREATE PROCEDURE p1()
BEGIN
SELECT*FROM student;
INSERT into teacher(tname) VALUES("ct");
END//delimiter ;
call p1()
importpymysql
conn= pymysql.connect(host='127.0.0.1',user='root',password='123',database='homework666',charset='utf8')
cursor=conn.cursor()
cursor.callproc('p1',(12,2))
conn.commit()
result=cursor.fetchall()print(result)
cursor.close()
conn.close()
1. 简单
create procedure p1()
BEGIN
select * from student;
INSERT into teacher(tname) values("ct");
END
call p1()
cursor.callproc('p1')
2. 传参数(in,out,inout)
delimiter //
create procedure p2(
in n1 int,
in n2 int
)
BEGIN
select * from student where sid > n1;
END //
delimiter ;
call p2(12,2)
cursor.callproc('p2',(12,2))
3.参数out
delimiter //
create procedure p3(
in n1 int,
out n2 int
)
BEGIN
set n2 = 123123;
select * from student where sid > n1;
END //
delimiter ;
set @v1=123;
call p3(12,@v1);
SELECT @v1;
importpymysql
conn= pymysql.connect(host='127.0.0.1',user='root',password='123',database='homework666',charset='utf8')
cursor=conn.cursor()
cursor.callproc('p3',(12,2))
r1=cursor.fetchall()print(r1)
cursor.execute('select @_p3_0,@_p3_1')
r2=cursor.fetchall()print(r2)
cursor.close()
conn.close()
#事务：
'''delimiter \\
create PROCEDURE p5(
OUT p_return_code tinyint
)
BEGIN
DECLARE exit handler for sqlexception
BEGIN
-- ERROR
set p_return_code = 1;
rollback;
END;
START TRANSACTION;
DELETE from tb1;
insert into tb2(name)values('seven');
COMMIT;
-- SUCCESS
set p_return_code =2;
END\\
delimiter ;'''
#游标#1、声明游标#2、获取A表中数据#my_cursor select id,num form A#3、for row_id,row_num in my_cursor:#检测循环是否还有数据，如果无数据#break#insert into B(num) values(row_id+row_num)
'''delimiter //
create procedure p6()
begin
declare row_id int; -- 自定义变量1
declare row_num int; -- 自定义变量2
DECLARE done INT DEFAULT FALSE;
declare temp int;
DECLARE my_cursor CURSOR FOR select id,num from A;
DECLARE CONTINUE HANDLER FOR NOT FOUND SET done = TRUE;
open my_cursor;
xxoo: LOOP
fetch my_cursor into row_id,row_num;
if done then
leave xxoo;
END IF;
set temp = row_id+row_num;
insert into B(number) values(temp);
end loop xxoo;
close my_cursor;
end //
delimter;
执行：
call p6()'''
#动态执行SQL(防SQL注入)
'''伪代码
delimiter //
create procedure p7(
in tp1 varchar(225),
in arg int
)
begin
1.预检测某个东西 sql语句的合法性
2.格式化tpl + arg
3.执行SQL语句
set @xo =arg
PREPARE xxx FROM 'select * from student where sid > ?';
EXECUTE xxx USING @xo;
DEALLOCATE prepare prod;
end //
delimter;
call p7("select * from tb where id >?",9)'''
'''真实代码
delimiter \\
CREATE PROCEDURE p8 (
in nid int
)
BEGIN
set @nid = nid;
PREPARE prod FROM 'select * from student where sid > ?';
EXECUTE prod USING @nid;
DEALLOCATE prepare prod;
END\\
delimiter ;'''