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 student for each 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 for each ROW
-- BEGIN
--     INSERT into teacher(tname) VALUES(NEW.sname);
-- END //
-- delimiter ;