MySQL常用操作
1、查看库里面有哪些库
mysql> show databases; +--------------------+ | Database | +--------------------+ | information_schema | | discuz | | mysql | | test | +--------------------+ 4 rows in set (0.01 sec)
2、进入某个库（切换库）
mysql> use mysql Database changed mysql> use discuz Database changed
3、查看当前所在库
mysql> select database(); +------------+ | database() | +------------+ | discuz | +------------+ 1 row in set (0.00 sec)
4、查看用户
mysql> select user(); +----------------+ | user() | +----------------+ | root@localhost | +----------------+ 1 row in set (0.00 sec)
5、查看数据库版本
mysql> select version();
+------------+
| version() |
+------------+
| 5.1.73-log |
+------------+
1 row in set (0.00 sec)
6、查看discuz个库有哪些表
mysql> use discuz Database changed mysql> show tables; +-----------------------------------+ | Tables_in_discuz | +-----------------------------------+ | pre_common_admincp_cmenu | | pre_common_admincp_group | | pre_common_admincp_member | +-----------------------------------+ 297 rows in set (0.00 sec)
7、查看表中有哪些字段
mysql> desc pre_ucenter_vars; +-------+-----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+-----------+------+-----+---------+-------+ | name | char(32) | NO | PRI | | | | value | char(255) | NO | | | | +-------+-----------+------+-----+---------+-------+ 2 rows in set (0.00 sec)
8、查看表中某行的创建过程
mysql> show create table pre_ucenter_vars\G; *************************** 1. row *************************** Table: pre_ucenter_vars Create Table: CREATE TABLE `pre_ucenter_vars` ( `name` char(32) NOT NULL DEFAULT '', `value` char(255) NOT NULL DEFAULT '', PRIMARY KEY (`name`) ) ENGINE=MEMORY DEFAULT CHARSET=gbk 1 row in set (0.00 sec) ERROR: No query specified
9、创建一个库实例
mysql> create database guozhen; 创建库
Query OK, 1 row affected (0.00 sec)
mysql> use guozhen; 进入库
Database changed
mysql> create table tb1 (`id` int(4), `name` char (40)) ENGINE=MYISAM DEFAULT CHARSET=gbk; 创建一个表
Query OK, 0 rows affected (0.00 sec)
mysql> show tables; 查看tables库有哪些表 +-------------------+ | Tables_in_guozhen | +-------------------+ | tb1 | +-------------------+ 1 row in set (0.00 sec) mysql> desc tb1; 查看tb1表中有哪些字段 +-------+----------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------+----------+------+-----+---------+-------+ | id | int(4) | YES | | NULL | | | name | char(40) | YES | | NULL | | +-------+----------+------+-----+---------+-------+ 2 rows in set (0.00 sec) mysql> show create table tb1\G; 查看tb1创建过程 *************************** 1. row *************************** Table: tb1 Create Table: CREATE TABLE `tb1` ( `id` int(4) DEFAULT NULL, `name` char(40) DEFAULT NULL ) ENGINE=MyISAM DEFAULT CHARSET=gbk 1 row in set (0.00 sec) ERROR: No query specified
10、插入一行或者字段
mysql> insert into tb1 values(1,'gz'); 插入一行
Query OK, 1 row affected (0.00 sec)
mysql> select * from tb1; 查看插入的行
+------+------+
| id | name |
+------+------+
| 1 | gz |
+------+------+
1 row in set (0.00 sec)
mysql> insert into tb1 (`id`) values(3); 只插入一个ID字段
Query OK, 1 row affected (0.00 sec)
mysql> select * from tb1;
+------+------+
| id | name |
+------+------+
| 1 | gz |
| 3 | NULL |
+------+------+
mysql> insert into tb1 (`name`) values('55'); 只插入一个name字段
Query OK, 1 row affected (0.00 sec)
mysql> select * from tb1;
+------+------+
| id | name |
+------+------+
| 1 | gz |
| 3 | NULL |
| NULL | 55 |
+------+------+
3 rows in set (0.00 sec)
mysql> insert into tb1 (`name`,`id`) values('linux3',5); 也可以字段颠倒顺序插入
Query OK, 1 row affected (0.00 sec)
mysql> select * from tb1;
+------+--------+
| id | name |
+------+--------+
| 1 | gz |
| 3 | NULL |
| NULL | 55 |
| 5 | linux3 |
+------+--------+
4 rows in set (0.00 sec)
11、更新某行（修改）
mysql> update tb1 set id=5 where name='55'; 更新某行 Query OK, 1 row affected (0.00 sec) Rows matched: 1 Changed: 1 Warnings: 0 mysql> select * from tb1; +------+--------+ | id | name | +------+--------+ | 1 | gz | | 3 | NULL | | 5 | 55 | | 5 | linux3 | +------+--------+ 4 rows in set (0.00 sec)
12、删除行、表、库
mysql> delete from tb1 where name='55'; 删除指定的行 Query OK, 1 row affected (0.00 sec) mysql> select * from tb1; +------+--------+ | id | name | +------+--------+ | 1 | gz | | 3 | NULL | | 5 | linux3 | +------+--------+ 3 rows in set (0.00 sec) mysql> truncate table tb1; 清空某个表，该表还在。 Query OK, 0 rows affected (0.00 sec) mysql> select * from tb1; 查看已经空了 Empty set (0.00 sec) mysql> drop table tb1; 删除某个表 Query OK, 0 rows affected (0.00 sec) mysql> select * from tb1; 查看时已然不存在 ERROR 1146 (42S02): Table 'guozhen.tb1' doesn't exist mysql> drop database guozhen; 删除某个库 Query OK, 0 rows affected (0.01 sec) mysql> show databases; 查看已然不存在 +--------------------+ | Database | +--------------------+ | information_schema | | discuz | | mysql | | test | +--------------------+ 4 rows in set (0.00 sec)
13、查看队列
mysql> show processlist; +----+------+-----------+------+---------+------+-------+------------------+ | Id | User | Host | db | Command | Time | State | Info | +----+------+-----------+------+---------+------+-------+------------------+ | 28 | root | localhost | NULL | Query | 0 | NULL | show processlist | +----+------+-----------+------+---------+------+-------+------------------+ 1 row in set (0.00 sec)
14、查看变量参数
mysql> show variables;
更改某个变量值（例：max_connections原值为151）
mysql> set global max_connections=200; //修改变量值
mysql> show variables like 'max_connections'; //过滤出该值
注：这样重启还是会恢复原值，所以我们要想永远改变，则要去/etc/my.cnf配置文件中修改该值。
15、查看状态
mysql> show status;
mysql> show status like '%running'; //过滤running的；%为万能通配，相当于shell下的*
16、修复表
mysql> repair table discuz.pre_forum_post; //discuz.pre_forum_post是你要修复的表名