mysql经常使用操做

mysql> show databases; #查看都有那些库#

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

| Database |

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

| information_schema |

| discuz |

| mysql |

| test |

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

4 rows in set (0.00 sec)

mysql> use discuz; #使用那个库#

Database changed

mysql> show tables; #查看库里边的表#

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

| Tables_in_discuz |

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

| pre_common_admincp_cmenu |

| pre_common_admincp_group |

| pre_common_admincp_member |

| pre_common_admincp_perm |

| pre_common_admincp_session |

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

297 rows in set (0.01 sec)

mysql> desc pre_forum_poll; #查看某个表的字段#

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

| Field | Type | Null | Key | Default | Extra |

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

| tid | mediumint(8) unsigned | NO | PRI | 0 | |

| overt | tinyint(1) | NO | | 0 | |

| multiple | tinyint(1) | NO | | 0 | |

| visible | tinyint(1) | NO | | 0 | |

| maxchoices | tinyint(3) unsigned | NO | | 0 | |

| isimage | tinyint(1) | NO | | 0 | |

| expiration | int(10) unsigned | NO | | 0 | |

| pollpreview | varchar(255) | NO | | | |

| voters | mediumint(8) unsigned | NO | | 0 | |

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

9 rows in set (0.03 sec)

mysql> show create table pre_forum_poll\G; #查看建表语句，加\G格式化好看点，不加显示很乱#

*************************** 1. row ***************************

Table: pre_forum_poll

Create Table: CREATE TABLE `pre_forum_poll` (

`tid` mediumint(8) unsigned NOT NULL DEFAULT '0',

`overt` tinyint(1) NOT NULL DEFAULT '0',

`multiple` tinyint(1) NOT NULL DEFAULT '0',

`visible` tinyint(1) NOT NULL DEFAULT '0',

`maxchoices` tinyint(3) unsigned NOT NULL DEFAULT '0',

`isimage` tinyint(1) NOT NULL DEFAULT '0',

`expiration` int(10) unsigned NOT NULL DEFAULT '0',

`pollpreview` varchar(255) NOT NULL DEFAULT '',

`voters` mediumint(8) unsigned NOT NULL DEFAULT '0',

PRIMARY KEY (`tid`)

) ENGINE=MyISAM DEFAULT CHARSET=gbk #引擎，字符集#

1 row in set (0.00 sec)

ERROR:

No query specified

mysql> select user(); #查看当前登录的用户#

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

| user() |

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

| root@localhost |

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

1 row in set (0.01 sec)

mysql> select database(); #查看当前使用的库#

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

| database() |

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

| discuz |

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

1 row in set (0.00 sec)

mysql> create database db1; #建立数据库#

Query OK, 1 row affected (0.01 sec)

mysql> show databases;

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

| Database |

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

| information_schema |

| db1 | #刚才建立的数据库#

| discuz |

| mysql |

| test |

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

5 rows in set (0.00 sec)

mysql> use db1; #使用db1库#

Database changed

mysql> create table `tab1`(`id` int(4), `name` char(50)) ENGINE=MyISAM DEFAULT CHARSET=gbk; #建立一个tab1表，表的第一个字段为id,类型int为整型最多为四位，第二个字段是name，类型为字符串类型，最多为50个字符，后边能够指定它的引擎和字符集。#

Query OK, 0 rows affected (0.00 sec)

mysql> show create table tab1\G; #查看刚才建的表tab1的语句#

*************************** 1. row ***************************

Table: tab1

Create Table: CREATE TABLE `tab1` (

`id` int(4) DEFAULT NULL,

`name` char(50) DEFAULT NULL

) ENGINE=MyISAM DEFAULT CHARSET=gbk

1 row in set (0.00 sec)

ERROR:

No query specified

mysql> create table `tb2` (`id` int(4),`name` char(40)); #建立表tb2,不指定引擎和字符集#

Query OK, 0 rows affected (0.01 sec)

mysql> show create table tb2\G; #查看表二的建表语句#

*************************** 1. row ***************************

Table: tb2

Create Table: CREATE TABLE `tb2` (

`id` int(4) DEFAULT NULL,

`name` char(40) DEFAULT NULL

) ENGINE=MyISAM DEFAULT CHARSET=latin1 #默认为myisam引擎，字符集是拉丁，可在配置文件修改，为防止乱码，可在建表的时候，指定字符集或在配置文件修改字符集#

1 row in set (0.00 sec)

ERROR:

No query specified

mysql> select version(); #查看数据库版本#

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

| version() |

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

| 5.1.73-log |

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

1 row in set (0.00 sec)

mysql> insert into tab1 (id,name)values(1,'wang'); #给表tab1插入数据,name为字符，要加单引号#

Query OK, 1 row affected (0.00 sec)

mysql> insert tab1(id,name)values(2,'li');

Query OK, 1 row affected (0.00 sec)

mysql> insert tab1 (id)values(3); #只插id#

Query OK, 1 row affected (0.00 sec)

mysql> insert tab1 (name)values('zhang');#只插name#

Query OK, 1 row affected (0.00 sec)

mysql> select * from tab1; #查询表tab1的数据#

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

| id | name |

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

| 1 | wang |

| 2 | li |

| 3 | NULL |

| NULL | zhang |

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

4 rows in set (0.00 sec)

mysql> update tab1 set id=3 where name='zhang'; #更改表tab1的id字段是3，name字段是zhang的行#

Query OK, 1 row affected (0.00 sec)

Rows matched: 1 Changed: 1 Warnings: 0

mysql> select * from tab1; #显示表中的数据#

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

| id | name |

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

| 1 | li |

| 2 | liu |

| 3 | zhang |

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

3 rows in set (0.00 sec)

mysql> delete from tab1 where name='liu'; #删除tab1表中name是liu 的行#

Query OK, 1 row affected (0.01 sec)

mysql> select * from tab1;

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

| id | name |

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

| 1 | li |

| 3 | zhang |

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

2 rows in set (0.00 sec)

mysql> truncate table tab1; #清空tab1表中的全部数据但不删除表#

Query OK, 0 rows affected (0.00 sec)

mysql> select * from tab1;

Empty set (0.00 sec)

mysql> drop table tab1; #删除整个表#

Query OK, 0 rows affected (0.00 sec)

mysql> show databases; #查看数据库#

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

| Database |

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

| information_schema |

| db1 |

| db2 |

| discuz |

| mysql |

| test |

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

6 rows in set (0.00 sec)

mysql> drop database db2; #删除数据库db2#

Query OK, 0 rows affected (0.04 sec)

mysql> show databases; #显示没有db2了#

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

| Database |

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

| information_schema |

| db1 |

| discuz |

| mysql |

| test |

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

5 rows in set (0.00 sec)

mysql> select version(); #显示数据库版本

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

| version() |

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

| 5.6.35 |

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