数据库基本操作命令
文章目录
mysql查看数据库结构
查看数据库结构
创建及删除库和表
管理表的记录
登录数据库
[root@localhost ~]# mysql -u root -p
Enter password:
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.7.20 Source distribution
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
查看数据库信息
查看数据库中的数据表信息
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
使用库
use 数据库名
mysql> use mysql;
Database changed
show tables
mysql> show tables;
+---------------------------+
| Tables_in_mysql |
+---------------------------+
| columns_priv |
| db |
| engine_cost |
| event |
| func |
| general_log |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| ndb_binlog_index |
| plugin |
| proc |
| procs_priv |
| proxies_priv |
| server_cost |
| servers |
| slave_master_info |
| slave_relay_log_info |
| slave_worker_info |
| slow_log |
| tables_priv |
| time_zone |
| time_zone_leap_second |
| time_zone_name |
| time_zone_transition |
| time_zone_transition_type |
| user |
+---------------------------+
31 rows in set (0.00 sec)
显示数据表的结构（字段）
describe [数据库名.]表名
mysql> desc servers;
+-------------+----------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------------+----------+------+-----+---------+-------+
| Server_name | char(64) | NO | PRI | | |
| Host | char(64) | NO | | | |
| Db | char(64) | NO | | | |
| Username | char(64) | NO | | | |
| Password | char(64) | NO | | | |
| Port | int(4) | NO | | 0 | |
| Socket | char(64) | NO | | | |
| Wrapper | char(64) | NO | | | |
| Owner | char(64) | NO | | | |
+-------------+----------+------+-----+---------+-------+
9 rows in set (0.00 sec)
SQL操作管理命令
SQL语言概述
SQL语言
是Structured Query Language的缩写，及结构化查询语言
是关系型数据库的标准语言
用于维护管理数据库，如数据查询，数据更新，访问控制，对象管理等功能
SQL分类
DDL：数据定义语言
DML：数据操纵语言
DQL：数据查询语言
DCL：数据控制语言
DDL操作命令
创建数据库和表
DDL语句用于创建数据库对象，如库，表，索引等
使用DDL语句新建库、表
DDL语句创建库、表的命令
创建数据库：create database 数据库名
mysql> create database school;
Query OK, 1 row affected (0.01 sec)
创建数据表：create table 表名（字段定义…）
mysql> use school;
Database changed
mysql> create table student (id int(3) not null primary key auto_increment,name varchar(10) not null,score decimal(5,2),address varchar(50) default '未知');
Query OK, 0 rows affected (0.02 sec)
DDL语句删除库，表的命令
删除指定的数据表：drop table [数据库名.]表名
mysql> use school;
Database changed
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
+------------------+
1 row in set (0.00 sec)
mysql> drop table student;
Query OK, 0 rows affected (0.01 sec)
mysql> show tables;
Empty set (0.00 sec)
删除指定的数据库：drop database 数据库名
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| school |
| sys |
+--------------------+
5 rows in set (0.00 sec)
mysql> drop database school;
Query OK, 0 rows affected (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.00 sec)
DML操作命令
DML语句的作用
DML语句用于对表中的数据进行管理
包括以下操作
mysql> select * from student;
Empty set (0.00 sec)
insert：插入新数据
update：更新原有数据
delete：删除不需要的数据
向数据表中插入新的数据记录命令
mysql> use school;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
+------------------+
1 row in set (0.00 sec)
mysql> select * from student;
Empty set (0.00 sec)
mysql> desc student;
+---------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+----------------+
| id | int(3) | NO | PRI | NULL | auto_increment |
| name | varchar(10) | NO | | NULL | |
| score | decimal(5,2) | YES | | NULL | |
| address | varchar(50) | YES | | 未知 | |
+---------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
mysql> insert into student(id,name,score,address) values(1,'zhangsan',99,'beijing');
Query OK, 1 row affected (0.01 sec)
mysql> select * from student;
+----+----------+-------+---------+
| id | name | score | address |
+----+----------+-------+---------+
| 1 | zhangsan | 99.00 | beijing |
+----+----------+-------+---------+
1 row in set (0.00 sec)
mysql> insert into student(name,score,address) values('lisi',65,'shanghai');
Query OK, 1 row affected (0.01 sec)
mysql> select * from student;
+----+----------+-------+----------+
| id | name | score | address |
+----+----------+-------+----------+
| 1 | zhangsan | 99.00 | beijing |
| 2 | lisi | 65.00 | shanghai |
+----+----------+-------+----------+
2 rows in set (0.00 sec)
mysql> insert into student values(3,'wangwu',98,default);
Query OK, 1 row affected (0.00 sec)
mysql> select * from student;
+----+----------+-------+----------+
| id | name | score | address |
+----+----------+-------+----------+
| 1 | zhangsan | 99.00 | beijing |
| 2 | lisi | 65.00 | shanghai |
| 3 | wangwu | 98.00 | 未知 |
+----+----------+-------+----------+
3 rows in set (0.00 sec)
mysql> insert into student(name,score,address) values('zhaoliu',59,'suzhou'),('lilei',68,'nanjing'),('hanmeimei',99,'shanghai');
Query OK, 3 rows affected (0.00 sec)
Records: 3 Duplicates: 0 Warnings: 0
mysql> select * from student;
+----+-----------+-------+----------+
| id | name | score | address |
+----+-----------+-------+----------+
| 1 | zhangsan | 99.00 | beijing |
| 2 | lisi | 65.00 | shanghai |
| 3 | wangwu | 98.00 | 未知 |
| 4 | zhaoliu | 59.00 | suzhou |
| 5 | lilei | 68.00 | nanjing |
| 6 | hanmeimei | 99.00 | shanghai |
+----+-----------+-------+----------+
6 rows in set (0.01 sec)
修改，更新数据表中的数据记录的命令
update 表名 set 字段名 1=值1[，字段名2=值2] where条件表达式
mysql> update student set score=66 where name='zhangsan';
Query OK, 1 row affected (0.01 sec)
Rows matched: 1 Changed: 1 Warnings: 0
mysql> select * from student;
+----+-----------+-------+----------+
| id | name | score | address |
+----+-----------+-------+----------+
| 1 | zhangsan | 66.00 | beijing |
| 2 | lisi | 65.00 | shanghai |
| 3 | wangwu | 98.00 | 未知 |
| 4 | zhaoliu | 59.00 | suzhou |
| 5 | lilei | 68.00 | nanjing |
| 6 | hanmeimei | 99.00 | shanghai |
+----+-----------+-------+----------+
6 rows in set (0.00 sec)
在数据表中删除指定的数据记录命令
delete from 表名 where 条件表达式
不带where条件的语句表示删除表中所有记录（高危操作）
mysql> delete from student where socre > 80;
ERROR 1054 (42S22): Unknown column 'socre' in 'where clause'
mysql> mysql> delete from student where score > 80;
Query OK, 2 rows affected (0.00 sec)
mysql> select * from student;
+----+----------+-------+----------+
| id | name | score | address |
+----+----------+-------+----------+
| 1 | zhangsan | 66.00 | beijing |
| 2 | lisi | 65.00 | shanghai |
| 4 | zhaoliu | 59.00 | suzhou |
| 5 | lilei | 68.00 | nanjing |
+----+----------+-------+----------+
4 rows in set (0.00 sec)
查看表结构命令
mysql> desc student;
+---------+--------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+---------+--------------+------+-----+---------+----------------+
| id | int(3) | NO | PRI | NULL | auto_increment |
| name | varchar(10) | NO | | NULL | |
| score | decimal(5,2) | YES | | NULL | |
| address | varchar(50) | YES | | 未知 | |
+---------+--------------+------+-----+---------+----------------+
4 rows in set (0.00 sec)
修改用户登录mysql的密码
忘记密码
[root@localhost ~]# vim /etc/my.cnf
skip-grant-tables
[root@localhost ~]# mysql -u root -p
Enter password: //不用输入密码，直接回车登录
Welcome to the MySQL monitor. Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.7.20 Source distribution
Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.
Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
mysql> update mysql.user set authentication_string=password('123456') where user='root';
Query OK, 1 row affected, 1 warning (0.00 sec)
Rows matched: 1 Changed: 1 Warnings: 1
mysql> quit
Bye
[root@localhost ~]# systemctl restart mysqld
DQL操作命令
DQL语句的作用
DQL是数据查询语句，只有一条：select
用于从数据表中查找符合条件的数据记录
不指定条件查询命令
select字段名1，字段名2…from表名
指定条件查询的命令
select字段名1，字段名2…from表名 WHERE 条件表达式
mysql> select * from student where score > 80;
+----+-----------+-------+----------+
| id | name | score | address |
+----+-----------+-------+----------+
| 3 | wangwu | 98.00 | 未知 |
| 6 | hanmeimei | 99.00 | shanghai |
+----+-----------+-------+----------+
2 rows in set (0.00 sec)
mysql> create table tmp as select * from student where score > 80;
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
| tmp |
+------------------+
2 rows in set (0.00 sec)
3 rows in set (0.00 sec)
DCL操作命令
DCL语句的作用
设置或查看用户的权限，或者创建用户
设置用户权限的命令
若用户已存在，则更改用户密码
若用户不存在，则新建用户
grant 权限列表 on 数据库名.表名 to 用户名@来源地址 identified by ‘密码′
mysql> grant all privileges on *.* to 'root'@'%' identified by 'abc123' with grant option;
Query OK, 0 rows affected, 1 warning (0.00 sec)
查看用户权限的命令
show grants for 用户名@来源地址
mysql> show grants;
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> show grants for 'root'@'localhost';
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.01 sec)
撤销用户权限的命令
revoke 权限列表 on 数据库名.表名 from 用户名@来源地址
mysql> show grants;
+---------------------------------------------------------------------+
| Grants for root@localhost |
+---------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+---------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> revoke all on *.* from 'root'@'localhost';
Query OK, 0 rows affected (0.00 sec)
mysql> show grants;
+--------------------------------------------------------------+
| Grants for root@localhost |
+--------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'root'@'localhost' WITH GRANT OPTION |
| GRANT PROXY ON ''@'' TO 'root'@'localhost' WITH GRANT OPTION |
+--------------------------------------------------------------+
2 rows in set (0.00 sec)
数据库高级操作
清空表
delete from tablename
truncate table tablename
mysql> use school;
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
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
| tmp |
+------------------+
2 rows in set (0.00 sec)
mysql> select * from tmp;
+----+-----------+-------+----------+
| id | name | score | address |
+----+-----------+-------+----------+
| 3 | wangwu | 98.00 | 未知 |
| 6 | hanmeimei | 99.00 | shanghai |
+----+-----------+-------+----------+
2 rows in set (0.00 sec)
mysql> delete from tmp;
Query OK, 2 rows affected (0.00 sec)
mysql> select * from tmp;
Empty set (0.00 sec)
临时表
临时建立的表，用于保存一些临时数据，不会长期存在（连接断开，临时表被删除）
mysql> create temporary table temp_info (id int(4) not null auto_increment,name varchar(10) not null,hobbby varchar(10) not null,primary key(id))engine=innodb default charset=utf8;
Query OK, 0 rows affected (0.00 sec)
mysql> desc temp_info;
+-------+-------------+------+-----+---------+----------------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+----------------+
| id | int(4) | NO | PRI | NULL | auto_increment |
| name | varchar(10) | NO | | NULL | |
| hobby | varchar(10) | NO | | NULL | |
+-------+-------------+------+-----+---------+----------------+
3 rows in set (0.00 sec)
mysql> show tables; '没有看到临时表，因为是放在内存当中'
+------------------+
| Tables_in_school |
+------------------+
| student |
| tmp |
+------------------+
2 rows in set (0.00 sec)
克隆表
直接克隆
mysql> create table kelong as select * from info; '克隆表结构和数据'
Query OK, 2 rows affected (0.01 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
| kelong |
| tmp |
+------------------+
3 rows in set (0.00 sec)
like方法
从表完整复制结构生成新表，再导入数据
mysql> create table k like info; '相比较like不能克隆表中的数据'
Query OK, 0 rows affected (0.02 sec)
mysql> show tables;
+------------------+
| Tables_in_school |
+------------------+
| student |
| k |
| kelong |
| tmp |
+------------------+
4 rows in set (0.00 sec)
mysql> select * from k;
Empty set (0.00 sec)
mysql> insert into k select * from info;
Query OK, 2 rows affected (0.00 sec)
Records: 2 Duplicates: 0 Warnings: 0
mysql> select * from k;
+----+----------+-------+----------+
| id | name | score | address |
+----+----------+-------+----------+
| 1 | zhangsan | 66.00 | nanjing |
| 3 | wangwu | 77.00 | hangzhou |
+----+----------+-------+----------+
2 rows in set (0.00 sec)
show create table方法
mysql> show create table student\G;
*************************** 1. row ***************************
Table: student
Create Table: CREATE TABLE `student` (
`id` int(3) NOT NULL AUTO_INCREMENT,
`name` varchar(10) NOT NULL,
`score` decimal(5,2) DEFAULT NULL,
`address` varchar(50) DEFAULT '未知',
PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8
1 row in set (0.00 sec)
ERROR:
No query specified