Linux运维必会MySQL 30道基础命令

1.1登录数据库

mysql-uroot -poldboy123 -S/data/3306/mysql.sock

1.2查看数据库版本及当前登录用户是什么？

mysql> select version();
+-----------+
| version() |
+-----------+
| 5.6.36 |
+-----------+
mysql>select user();
+----------------+
| user() |
+----------------+
| root@localhost |
+----------------+

1.3创建GBK字符集的数据库oldboy，并查看已建库的完整语句

mysql> create database oldboy2 character set gbk collate gbk_chinese_ci;
Query OK, 1 row affected (0.06 sec)

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| oldboy |
| oldboy2 |
| performance_schema |
| world |
+--------------------+
mysql> show create database oldboy;
+----------+-----------------------------------------------------------------+
| Database | Create Database |
+----------+-----------------------------------------------------------------+
| oldboy |CREATE DATABASE `oldboy` /*!40100 DEFAULT CHARACTER SET utf8 */ |
+----------+-----------------------------------------------------------------+

1.4创建用户oldboy，使之可以管理数据库oldboy

grant all on oldboy2.* to oldboy2@'localhost'identified by '123'

1.5查看创建的用户oldboy拥有哪些权利

mysql>show grants for oldboy2@'localhost';
+----------------------------------------------------------------------------------------------------------------+
| Grants for oldboy2@localhost |
+----------------------------------------------------------------------------------------------------------------+
| GRANT USAGE ON *.* TO 'oldboy2'@'localhost'IDENTIFIED BY PASSWORD '*23AE809DDACAF96AF0FD78ED04B6A265E05AA257' |
| GRANT ALL PRIVILEGES ON `oldboy2`.* TO'oldboy2'@'localhost' |
+----------------------------------------------------------------------------------------------------------------+

1.6查看当前数据库里有哪些用户

mysql>select user,host from mysql.user;
+---------+------------+
| user |host |
+---------+------------+
| oldboy1 | 10.0.0.% |
| root |127.0.0.1 |
| oldboy |172.16.1.% |
| oldboy2 | localhost |
| root |localhost |
+---------+------------+

1.7进入oldboy数据库

mysql> use oldboy2

1.8创建一innodb引擎字符集为GBK表test，字段为id和namevarchar(16)，查看建表结构及语句

1.8.1创建

mysql> use oldboy2
Database changed
mysql> create table test(
-> id int(4),
-> name varchar(16)
-> ) engine=innodb default charset=gbk;
Query OK, 0 rows affected (0.09 sec)

mysql> show tables;
+-------------------+
| Tables_in_oldboy2 |
+-------------------+
| test |
+-------------------+

1.8.2查看表结构

1.8.2.1 方法一：

mysql> desc test;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id |int(4) | YES | |NULL | |
| name |varchar(16) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+

1.8.2.2 方法二：

mysql>show columns from test;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id |int(4) | YES | |NULL | |
| name |varchar(16) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+

1.8.3查看表结构SQL语句

mysql>show create table test;
+-------+-------------------------------------------------------------------------------------------------------------------------+
| Table | Create Table |
+-------+-------------------------------------------------------------------------------------------------------------------------+
| test |CREATE TABLE `test` (
`id`int(4) DEFAULT NULL,
`name`varchar(16) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=gbk |
+-------+-------------------------------------------------------------------------------------------------------------------------+

1.9插入一条数据1,oldboy

mysql> insert into test values(1,'oldboy');
mysql> select * from test;
+------+--------+
| id |name |
+------+--------+
| 1 |oldboy |
+------+--------+

1.10批量插入数据 2，老男孩，3，etiantian.要求中文不能乱码

mysql> insert into test values(2,'老男孩'),(3,'etiantian');
mysql> select * from test ;
+------+-----------+
| id |name |
+------+-----------+
| 1 |oldboy |
| 2 | 老男孩 |
| 3 |etiantian |
+------+-----------+

1.11查询插入的所有记录，查询名字为oldboy的记录。查询id大于1的记录

1.11.1查看插入的所有记录

mysql>select * from test
-> ;
+------+-----------+
| id |name |
+------+-----------+
| 1 |oldboy |
| 2 | 老男孩 |
| 3 |etiantian |
+------+-----------+

1.11.2查询名字为oldboy的记录

mysql> select * from test where name='oldboy';
+------+--------+
| id |name |
+------+--------+
| 1 |oldboy |
+------+--------+

1.11.3查看id大于1的记录

mysql>select * from test where id>1;
+------+-----------+
| id |name |
+------+-----------+
| 2 | 老男孩 |
| 3 |etiantian |
+------+-----------+

1.12把数据id等于1的名字oldboy更改为oldbgirl

updatetest set name='oldgirl' where id=1;
mysql>select * from test;
+------+-----------+
| id |name |
+------+-----------+
| 1 |oldgirl |
| 2 | 老男孩 |
| 3 |etiantian |
+------+-----------+

1.13在字段name前插入age字段，类型tinyint(2)

mysql>alter table test add age tinyint(2)after id;
mysql> desc test;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id |int(4) | YES | |NULL | |
| age |tinyint(2) | YES | |NULL | |
| name |varchar(16) | YES | | NULL | |
+-------+-------------+------+-----+---------+-------+

1.14备份oldboy库及Mysql库

mysqldump –B –compact oldboy > /opt/bak.sql

1.15删除表中的所有数据，并查看

1.15.1delete是逻辑删除表中的数据，一列一列的删除表中的数据，速度比较慢

delete from rest;

1.15.2truncate是物理删除表中的数据，一次性全部都给清空表中数据，速度很快

truncate table test;

1.16删除表test和oldboy数据库并查看

1.16.1删除表

drop table test;

1.16.2删除数据库oldboy

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| oldboy |
| performance_schema |
+--------------------+
4 rows in set (0.00 sec)

mysql> drop database oldboy;
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
+--------------------+

1.17linux命令行恢复以上删除数据

mysql -uroot -poldboy123 -S/data/3306/mysql.sock</opt/bak.sql

1.18把GBK字符集修改为UTF8（可选,注意此题有陷阱）

1.18.1查看一下字符集

mysql> mysql> show variables like'character_set%';
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir |/application/mysql-5.6.36/share/charsets/ |
+--------------------------+-------------------------------------------+

1.18.2设置字符集

mysql> set global character_set_database =utf8;

1.19Mysql密码丢了，如何找回实战

1.20Mysql内中文数据乱码的原理及如何防止乱码

1.20.1数据库字符集

mysql> show variables like 'character_set%';
+--------------------------+-------------------------------------------+
| Variable_name | Value |
+--------------------------+-------------------------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir |/application/mysql-5.6.36/share/charsets/ |
+--------------------------+-------------------------------------------+

1.20.2系统字符配置文件

[root@mysql data]# cat /etc/sysconfig/i18n
LANG="en_US.UTF-8"
SYSFONT="latarcyrheb-sun16"

1.21 在把id列设置为主键，在name字段上创建普通索引

mysql> desc oldboy.test;
+-------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+-------+-------------+------+-----+---------+-------+
| id |int(4) | YES | |NULL | |
| name |varchar(16) | YES | | NULL | |
| age |int(4) | YES | |NULL | |
+-------+-------------+------+-----+---------+-------+
alter table oldboy.test add primarykey(id);

1.21.1在name字段上创建普通索引

方法一：alter table oldboy,test addindexindex_name(name)
方法二：create index index_name onoldboy.test(name);

1.22在字段name后插入手机号字段（shouji）,类型char(11)

mysql> alter table test add shou char(11) aftername;
mysql> desc test;
+--------+-------------+------+-----+---------+-------+
| Field |Type | Null | Key | Default |Extra |
+--------+-------------+------+-----+---------+-------+
| id |int(4) | YES | MUL | NULL | |
| name |varchar(16) | YES | | NULL | |
| shou |char(11) | YES | |NULL | |
| age |int(4) | YES | |NULL | |
| shouji | char(11) | YES | | NULL | |
+--------+-------------+------+-----+---------+-------+

1.23所有字段上插入两条记录（自行设定数据）

mysql> insert into test values(6,'mysql','mei','21','1794225527'),(7,'mysql1','mein','21','15095,'15095445967');
mysql> select * from test;
+------+---------+------+------+-------------+
| id |name | shou | age | shouji |
+------+---------+------+------+-------------+
| 1 |oldboy | NULL | 21 | NULL |
| 3 |oldboy3 | NULL | 21 | NULL |
| 4 |oldboy4 | NULL | 21 | NULL |
| 5 | 小明 | NULL | 21 | NULL |
| 6 |mysql | mei | 21| 1794225527 |
| 7 |mysql1 | mein | 21 | 15095445967 |
+------+---------+------+------+-------------+

1.24在手机字段上对前八个字符创建普通索引

mysql> alter table test add index index_shouji(shouji(8));
mysql> desc test;
+--------+-------------+------+-----+---------+-------+
| Field |Type | Null | Key | Default |Extra |
+--------+-------------+------+-----+---------+-------+
| id |int(4) | YES | MUL | NULL | |
| name |varchar(16) | YES | | NULL | |
| shou |char(11) | YES | |NULL | |
| age |int(4) | YES | | NULL | |
| shouji | char(11) | YES | MUL | NULL | |
+--------+-------------+------+-----+---------+-------+

1.25查看创建的索引及索引类型等信息

mysql>mysql> show index from test\G
*************************** 1. row ***************************
Table: test
Non_unique: 1
Key_name: name_idx
Seq_in_index: 1
Column_name: id
Collation: A
Cardinality: 6
Sub_part: NULL
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
*************************** 2. row***************************
Table: test
Non_unique: 1
Key_name: index_shouji
Seq_in_index: 1
Column_name: shouji
Collation: A
Cardinality: 6
Sub_part: 8
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
2 rows in set (0.00 sec

1.26删除name，shouji列的索引

mysql> alter table test drop index index_shouji;
mysql> show index from test\G
*************************** 1. row***************************
Table: test
Non_unique: 1
Key_name: name_idx
Seq_in_index: 1
Column_name: id
Collation: A
Cardinality: 6
Sub_part: NULL
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
1 row in set (0.00 sec)

1.27对name列的前6个字符以及手机列的前8个字符组建联合索引

alter table test add indexindex_name_shouji(name(6),shouji(8));
mysql> show index from test\G
*************************** 1. row***************************
Table: test
Non_unique: 1
Key_name: name_idx
Seq_in_index: 1
Column_name: id
Collation: A
Cardinality: 6
Sub_part: NULL
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
*************************** 2. row***************************
Table: test
Non_unique: 1
Key_name: index_name_shouji
Seq_in_index: 1
Column_name: name
Collation: A
Cardinality: 6
Sub_part: 6
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
*************************** 3. row***************************
Table: test
Non_unique: 1
Key_name: index_name_shouji
Seq_in_index: 2
Column_name: shouji
Collation: A
Cardinality: 6
Sub_part: 8
Packed: NULL
Null: YES
Index_type: BTREE
Comment:
Index_comment:
3 rows in set (0.00 sec)

1.28查询手机号以136开头的，名字为oldboy的记录（次记录要提前插入）

mysql> select * from test where name='mysql'and shouji like '179%';
+------+-------+------+------+------------+
| id |name | shou | age | shouji |
+------+-------+------+------+------------+
| 6 |mysql | mei | 21 | 1794225527 |
+------+-------+------+------+------------+

1.29查询上述语句的执行计划（是否使用联合索引等）

mysql> explain select * from test wherename='oldboy' and shouji like '1%';
+----+-------------+-------+-------+-------------------+-------------------+---------+------+------+-------------+
| id | select_type | table | type | possible_keys | key | key_len | ref | rows | Extra |
+----+-------------+-------+-------+-------------------+-------------------+---------+------+------+-------------+
| 1 |SIMPLE | test | range | index_name_shouji |index_name_shouji | 32 | NULL | 1 | Using where |
+----+-------------+-------+-------+-------------------+-------------------+---------+------+------+-------------+
mysql> explain select * from test where name='oldboy' and shouji like '1%'\G
*************************** 1. row***************************
id: 1
select_type: SIMPLE
table: test
type: range
possible_keys: index_name_shouji
key: index_name_shouji
key_len: 32
ref: NULL
rows: 1
Extra: Using where
1 row in set (0.00 sec)

1.30把test的引擎改成Mysql

mysql> show create table test\G
*************************** 1. row***************************
Table: test
Create Table: CREATE TABLE `test` (
`id`int(4) DEFAULT NULL,
`name`varchar(16) DEFAULT NULL,
`shou`char(11) DEFAULT NULL,
`age`int(4) DEFAULT NULL,
`shouji`char(11) DEFAULT NULL,
KEY`name_idx` (`id`),
KEY`index_name_shouji` (`name`(6),`shouji`(8))
) ENGINE=InnoDB DEFAULT CHARSET=gbk

mysql> alter table oldboy.test ENGINE=MyISAM;
Query OK, 5 rows affected (0.01 sec)
Records: 5 Duplicates: 0 Warnings: 0

mysql> show create table oldboy.test\G
*************************** 1. row***************************
Table: test
Create Table: CREATE TABLE `test` (
`id`int(4) NOT NULL DEFAULT'0',
`age`tinyint(2) DEFAULTNULL,
`name`varchar(16) DEFAULTNULL,
`shouji`char(11) DEFAULTNULL,
PRIMARYKEY (`id`),
KEY`index_name_shouji`(`name`(6),`shouji`(8))
) ENGINE=MyISAM DEFAULT CHARSET=gbk
1 row in set (0.00 sec)