兄弟连(python)---------mysql日常随笔
- 创建视图
mysql> create view v1 as select * from t2;
Query OK, 0 rows affected (0.02 sec)
删除主表的时候 那么视图表就不起作用了
mysql> drop table t2;
Query OK, 0 rows affected (0.02 sec)
mysql> select * from v1;
ERROR 1356 (HY000): View 'python.v1' references invalid table(s) or column(s) or function(s) or definer/invoker of view
mysql> show tables;
删除视图表
mysql> drop view v1;
Query OK, 0 rows affected (0.00 sec)
- MySQL内部函数
mysql> select ucase('name') from stu; -----这个含义是让字符串name变成大写而不是让name字段里面所有的值变成大写
+---------------+
| ucase('name') |
+---------------+
| NAME |
| NAME |
| NAME |
mysql> select ucase(name) from stu; -----这个含义是 让name字段里面的所有值变成大写
+------------------+
| ucase(name) |
+------------------+
| |
| 22WEW |
| 666 |
| AA |
| AABB |
| CAO |
| EEE |
- 命名别名
mysql> select length('dsjfkdsfiefuie');
如果不起别名的话那么现实出来的字段名就是你查询出来的名字
+--------------------------+
| length('dsjfkdsfiefuie') |
+--------------------------+
| 14 |
+--------------------------+
1 row in set (0.00 sec)
如果你起了别名，那么现实出来的名字就是你的别名
mysql> select length('dsfdsfdsfds') as len;
+-----+
| len |
+-----+
| 11 |
+-----+
1 row in set (0.00 sec)
给表名起一个别名 使用as
mysql> select a.name,c.childname from type as a,typechild as c where a.id = c.pid;
不使用 as
mysql> select a.name,c.childname from type a,typechild c where a.id = c.pid;
- MySQL预处理操作
mysql> prepare stmt from 'select * from stu where id > ?'
Query OK, 0 rows affected (0.01 sec)
Statement prepared
mysql> set @id = 5;
Query OK, 0 rows affected (0.00 sec)
mysql> execute stmt using @id;
+----+------------------+-----+-----+----------+
| id | name | age | sex | classid |
+----+------------------+-----+-----+----------+
| 7 | uu03 | 26 | m | lamp103 |
| 8 | uu04 | 27 | w | lamp105 |
- 存储过程 ????? 在mysql命令行中字符串和变量使用什么符号链接 +
mysql> create procedure intos(num int)
-> begin
-> set @i = 0;
-> while @i <= num do
-> insert into t3 values (2,'we232');
-> set @i = @i+1;
-> end while;
-> end#
Query OK, 0 rows affected (0.00 sec)
mysql> call intos(10)#
Query OK, 0 rows affected (0.04 sec)
- trigger触发器
创建触发器 tg5
mysql> create trigger tg5 after insert on t4 for each row
-> begin
-> update t5 set name='bbbb' where id = 2;
-> end#
Query OK, 0 rows affected (0.02 sec)
mysql> select * from t5#
+----+--------+
| id | name |
+----+--------+
| 1 | aaaa |
| 2 | ???? |
| 3 | 我很你 |
+----+--------+
3 rows in set (0.00 sec)
往t4表中插入数据的时候要改变t5表的信息
mysql> insert into t4(id,name) values (9,'wew23232')#
Query OK, 1 row affected (0.02 sec)
mysql> select * from t5#
+----+--------+
| id | name |
+----+--------+
| 1 | aaaa |
| 2 | bbbb |
| 3 | 我很你 |
+----+--------+
3 rows in set (0.00 sec)
