学习笔记mysql常用基本操作

Posted 2020-10-25

给mysql数据库root账号设定密码
[[email protected] ~]# mysqladmin -u root password ‘123456‘

连接数据库：
可以使用命令:mysql –u root –p连接数据库，但只是连接本地库，很多时间需要连接网络中的某台主机的数据库：
备注：-u 账号 -p 密码 -h 指定远程主机的ip
连接本地库：[[email protected] ~]# mysql -u root -p
Enter password:
连接网络中的库：[[email protected] ~]# mysql -uroot -p -h192.168.1.1 -P3306
Enter password:
-P：用来指定远程主机mysql的绑定端口，默认是3306

查询当前库：
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| test |
+--------------------+
3 rows in set (0.01 sec)

查询某个库中的表：
首先要切换到某个库中：
mysql> use mysql
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
-A可以忽略在切换库时读取所有表的字段
mysql> use mysql -A;
Database changed
列出全有的表：
mysql> show tables;
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| event |
| func |
| general_log |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| host |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| servers |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
23 rows in set (0.00 sec)

查看表的全部字段：
mysql> desc db;

\G:以行的形式显示：
mysql> desc db\G;
1. row

查看当前是哪个用户
mysql> select user();
+----------------+
| user() |
+----------------+
| [email protected] |
+----------------+
1 row in set (0.00 sec)

查看当前数据库的命令：
mysql> select database();
+------------+
| database() |
+------------+
| mysql |
+------------+
1 row in set (0.00 sec)

创建一个新库：
mysql> create database db1;
Query OK, 1 row affected (0.00 sec)
查看刚才创建的新库
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| db1 |
| mysql |
| test |
+--------------------+
4 rows in set (0.00 sec)

查看当前数据库的版本：
mysql> select version();
+-----------+
| version() |
+-----------+
| 5.1.73 |
+-----------+
1 row in set (0.00 sec)

查看MySQL的当前状态：
mysql> show status;
+-----------------------------------+----------+
| Variable_name | Value |
+-----------------------------------+----------+
| Aborted_clients | 0 |
| Aborted_connects | 3 |

查看MySQL的参数：
mysql> show variables;
查看当前mysql服务器的队列：
mysql> show processlist;
+----+------+-----------+-------+---------+------+-------+------------------+
| Id | User | Host | db | Command | Time | State | Info |
+----+------+-----------+-------+---------+------+-------+------------------+
| 11 | root | localhost | mysql | Query | 0 | NULL | show processlist |
+----+------+-----------+-------+---------+------+-------+------------------+
1 row in set (0.00 sec)

创建一个新表：
mysql> use db1; #切换到库里面先
Database changed
mysql> create table test(id int(20),name char(40));
Query OK, 0 rows affected (0.03 sec)
查看刚才创建的表：
mysql> desc test;
+-------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+----------+------+-----+---------+-------+
| id | int(20) | YES | | NULL | |
| name | char(40) | YES | | NULL | |
+-------+----------+------+-----+---------+-------+
2 rows in set (0.00 sec)

插入数据：
mysql> insert into test values (1,‘le‘);
Query OK, 1 row affected (0.00 sec)
查看表中的数据：
mysql> select * from test;
+------+------+
| id | name |
+------+------+
| 1 | le |
+------+------+
1 row in set (0.00 sec)

清空某个表中的数据：
mysql> truncate table test;
Query OK, 0 rows affected (0.00 sec)

查看表中的数据：
mysql> select * from test;
Empty set (0.00 sec)

创建一个普通用户并授权
mysql> grant all on . to user2 identified by ‘123456‘;
Query OK, 0 rows affected (0.00 sec)
All:表示有全部的权限
.:前者表示所有库，后者表示所有表
给网络的主机某个用户授权：
mysql> grant all on db1. to ‘user2‘@‘192.168.159.136‘ identified by ‘1234567’;
Query OK, 0 rows affected (0.00 sec)

查询语句：
第一种方法：
mysql> select count() from mysql.user;
+----------+
| count() |
+----------+
| 7 |
+----------+
1 row in set (0.00 sec)
Mysql.user表示MySQL库中的表，count(*)表示表中有多少行

第二种方法：
mysql> select db from mysql.db;
+---------+
| db |
+---------+
| test |
| test_% |
| db1 |
+---------+
3 rows in set (0.00 sec)

小弟是初学者，有错的地方希望大佬们点出来！