13.4 MySQL用户管理
1 创建user1用户
mysql> grant all on *.* to'user1'@'127.0.0.1' identified by '123456a';
Query OK, 0 rows affected (0.01 sec)
解释：
grant all 所有的权限
*.*xx库的xx表，如果是mysql库的表可以表示为mysql.*
@'127.0.0.1'授权指定源ip连接。所有ip通配表示为@'%',%表示所有ip
2 利用user1连接MySQL
如果没有指定ip连接，会出现以下报错，因为mysql默认socket连接，而user1授权指定了ip连接。
[[email protected] ~]# mysql -uuser1 -p123456a
Warning: Using a password on the command line interface can be insecure.
ERROR 1045 (28000): Access denied for user 'user'@'localhost' (using password: YES)
正确连接方式，
[[email protected] ~]# mysql -uuser1 -p123456a -h127.0.0.1
mysql>
2.1 授权localhost连接
利用root进入mysql修改，
[[email protected] ~]# mysql -uroot -paminglinux
mysql> grant all on *.* to'user1'@'localhost' identified by '123456a';
2.2 localhost相当于socket，所以在本机用user1连接mysql的话，直接连接
[[email protected] ~]# mysql -uuser1 -p123456a
mysql>
2.3 还可以针对性去设置用户给予权限
mysql> grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'192.168.133.1' identified by 'passwd';
3 查看用户的权限
查看当前用户的权限
mysql> show grants
查看user1的权限
mysql> show grants for [email protected]'127.0.0.1';
+-----------------------------------------------------------------------------------------------------------------------+
| Grants for [email protected] |
+-----------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'user1'@'127.0.0.1' IDENTIFIED BY PASSWORD '*B012E8731FF1DF44F3D8B26837708985278C3CED' |
+-----------------------------------------------------------------------------------------------------------------------+
3.1 添加user2，并针对指定权限
mysql> grant SELECT,UPDATE,INSERT on db1.* to 'user2'@'172.18.171.157' identified by 'passwd';
Query OK, 0 rows affected (0.00 sec)
mysql> show grants for [email protected]'172.18.171.157'
-> ;
+-------------------------------------------------------------------------------------------------------------------+
| Grants for [email protected] |
+-------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'user2'@'172.18.171.157' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0' |
| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'172.18.171.157' |
+-------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
3.2 在不知道用户密码的时候给予同样权限，例如给予172.18.171.158的user2.
我们复制即可show grants后的信息，更改IP地址172.18.171.158，然后再分别执行即可赋予同样权限。
mysql> GRANT USAGE ON *.* TO 'user2'@'172.18.171.158' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDDF46B68F5C8B8F25762BCCEF0'
-> ;
Query OK, 0 rows affected (0.00 sec)
mysql> GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'172.18.171.158';
Query OK, 0 rows affected (0.00 sec)
3.3 看158的用户权限信息。
mysql> show grants for user2 @'172.18.171.158'
-> ;
+-------------------------------------------------------------------------------------------------------------------+
| Grants for [email protected] |
+-------------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'user2'@'172.18.171.158' IDENTIFIED BY PASSWORD '*59C70DA2F3E3A5BDF46B68F5C8B8F25762BCCEF0' |
| GRANT SELECT, INSERT, UPDATE ON `db1`.* TO 'user2'@'172.18.171.158' |
+-------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)
13.5 常用sql语句
1 查看MySQL库里的user表有多少行
select count(*) from mysql.user;
mysql> select count(*) from mysql.user;
+----------+
| count(*) |
+----------+
| 11 |
+----------+
1 row in set (0.00 sec)
count(*)表示表中共有多少行，此处是11行。
这个是用MyIsam 的engine，相对InnoDB会比较快
2 查看表里所有的内容;
mysql> select * from mysql.db\G;
这里的*这个是用InnoDB的Engine 会比较慢，所以要慎用
3 查询单个或多个字段的数据
单个
select db from mysql.db;
mysql> select db from mysql.db;
+---------+
| db |
+---------+
| test |
| test\_% |
| db1 |
| db1 |
| db1 |
+---------+
5 rows in set (0.00 sec)
多个
select db,user from mysql.db;
mysql> select db,user from mysql.db;
+---------+-------+
| db | user |
+---------+-------+
| test | |
| test\_% | |
| db1 | user2 |
| db1 | user2 |
| db1 | user2 |
+---------+-------+
5 rows in set (0.00 sec)
4 模糊查询
mysql> select * from mysql.db where host like '172.%.%';
可以利用\G整洁显示
mysql> select * from mysql.db where host like '172.%.%'\G;
其中like就是起到了模糊匹配的作用
5 插入语句
db1.t1是一个空表,利用这个表测试。
mysql> desc db1.t1;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
mysql> select * from db1.t1;
Empty set (0.01 sec)
在db1.t1插入数据：两个字段（第一个字段是id,第二个字段是name）
mysql> insert into db1.t1 values (1, 'abc');
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
+------+------+
1 row in set (0.00 sec)
可以看到已被插入2个字段，分别是1和abc.
插入数据的时候要注意，插入字符串最好加上''，数字可以不用加''。
mysql> insert into db1.t1 values (1,'234');
Query OK, 1 row affected (0.00 sec)
mysql> insert into db1.t1 values (1,234);
Query OK, 1 row affected (0.00 sec)
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | abc |
| 1 | 234 |
| 1 | 234 |
+------+------+
3 rows in set (0.00 sec)
5.1 更改表的某一行的数据
update db1.t1 set name='aaa' where id=1;
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 1 | aaa |
| 1 | aaa |
| 1 | aaa |
+------+------+
3 rows in set (0.01 sec)
更改db1.t1里面匹配id=1 将name改成aaa值
5.2 同样可以匹配name改id
mysql> update db1.t1 set id=2 where name='aaa';
Query OK, 3 rows affected (0.01 sec)
Rows matched: 3 Changed: 3 Warnings: 0
mysql> select * from db1.t1;
+------+------+
| id | name |
+------+------+
| 2 | aaa |
| 2 | aaa |
| 2 | aaa |
+------+------+
3 rows in set (0.00 sec)
6 清空字段
mysql> delete from db1.t1 where id=2;
mysql> select * from db1.t1;
Empty set (0.00 sec)
6.1 清空表的内容,表结构保留
mysql>truncate table db1.t1;
mysql> desc db1.t1;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(4) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)
6.2 完全删除表
mysql>drop table db1.t1;
mysql> desc db1.t1;
ERROR 1146 (42S02): Table 'db1.t1' doesn't exist
6.3 干掉数据库
drop database db1;
mysql> drop database db1;
Query OK, 0 rows affected (0.00 sec)
mysql> use db1
ERROR 1049 (42000): Unknown database 'db1'
总结：
尽量在大数据库，表少用*来查看内容。
慎用删除功能。
原文地址：http://blog.51cto.com/13578154/2113971