兄弟連(python)---------mysql平常隨筆

1. 建立視圖

 

mysql> create view v1 as select * from t2;

Query OK, 0 rows affected (0.02 sec)

 

刪除主表的時候 那麼視圖表就不起做用了

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;

 

刪除視圖表

mysql> drop view v1;

Query OK, 0 rows affected (0.00 sec)

 

1. MySQL內部函數

mysql> select ucase('name') from stu;  -----這個含義是讓字符串name變成大寫而不是讓name字段裏面全部的值變成大寫

+---------------+

| ucase('name') |

+---------------+

| NAME          |

| NAME          |

| NAME          |

 

mysql> select ucase(name) from stu; -----這個含義是 讓name字段裏面的全部值變成大寫

+------------------+

| ucase(name)      |

+------------------+

|                  |

| 22WEW            |

| 666              |

| AA               |

| AABB             |

| CAO              |

| EEE              |

 

1. 命名別名

mysql> select length('dsjfkdsfiefuie');

若是不起別名的話那麼現實出來的字段名就是你查詢出來的名字

+--------------------------+

| length('dsjfkdsfiefuie') |

+--------------------------+

|             14 |

+--------------------------+

1 row in set (0.00 sec)

 

若是你起了別名，那麼現實出來的名字就是你的別名

mysql> select length('dsfdsfdsfds') as len;

+-----+

| len |

+-----+

|  11 |

+-----+

1 row in set (0.00 sec)

 

給表名起一個別名  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;

 

1. MySQL預處理操做

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  |

 

1. 存儲過程  ????? 在mysql命令行中字符串和變量使用什麼符號連接   +

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)

 

1. trigger觸發器

 

建立觸發器 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表中插入數據的時候要改變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)