MySQL常用命令基礎操作

阿新 • • 發佈：2018-11-03

host isp 創建表 fin err name p12 就是 local

MySQL啟動與更改密碼

mysql啟動基本原理說明：

/etc/init.d/mysqld是一個shell啟動腳本，啟動後最終會調用，mysqld_safe腳本，最後調用mysqld服務啟動mysql，我們編輯/etc/init.d/mysqld，可以看到腳本，啟動倆個進程mysqld和mysqld_safe，一般故障的時候我們用mysqld_safe來啟動，

關閉mysql

1 mysqladmin - uroot -p密碼 shut down
2 /etc/init.d/mysqld  stop
3 kill USR2`cat path/pid`

優雅的關閉mysql但是不建議用killall殺掉所有的mysql進程，這樣會導致mysql數據庫起不來，所以網友遇到這樣情況也很多，

我們登陸mysql後想分清出那個是正式環境那個是測試環境，

命令行修改登陸提示符

mysql> prompt\u@king\s->
PROMPT set to ‘\u@king\s->‘

配置文件修改登陸提示符

在my.cnf配置文件中[mysql]模塊下添加如下內容，保存後，無需重啟myysql，退出當前的session，重新登陸

[mysql]
prompt=\\u@king\s->

登陸mysql

[root @king~]# mysql
Welcome to the MySQL monitor.  Commands end with ; or \g.
Your MySQL connection id  
is 2
Server version: 5.5.40 MySQL Community Server (GPL)
Copyright (c) 2000, 2014, 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>

更改root密碼

1 mysql> update user set password=password(‘123456‘) where user=‘root‘ and host=‘localhost‘;  #password（‘12345‘）是指定一個函數
2 Query OK, 1 row affected (0.00 sec)
3 Rows matched: 1  Changed: 1  Warnings: 0
4 mysql> flush privileges;　　　　　　　　　　　　　　#刷新，沒刷新前是在內存裏面
5 Query OK, 0 rows affected (0.17 sec)
6 mysql>

說明，修改密碼都需要刷新一下哦，linux找回mysql root用戶密碼

單實例mysql修改丟失root方法

1，首先停止mysql

/etc/init.d/mysql stop

2，使用--skip-grant-tables啟動mysql，忽略授權登陸驗證

 1 mysqld_safe --user=mysql --skip-grant-tables --skip-networking &
 2 mysql -u root -p　　　　　　　　#說明-p登陸時密碼是空，也可以不加-p，親測哦(#^.^#)
 3 update mysql.user set password=password("newpassword") where user=‘root‘and host=‘localhost‘;
 4 mysql> flush privileges;
 5 mysql> quit
 6 # /etc/init.d/mysql restart
 7 # mysql -uroot -p
 8 enter password: <輸入新設的密碼newpassword>
 9 mysql>

多實例mysql修改丟失root方法

1關閉mysql

killall mysqld

2啟動時加--skip-grant-tables參數

mysql_safe --defaults-file=/data/3306/my.cnf --skip-grant-tables& mysql -u root -p -S /data/3306/mysql.sock

3修改密碼

mysql>update mysql.user set password=password("newpassword") where user=‘root‘and host=‘localhost‘;
mysql> flush privileges;
Query OK, 0 rows affected (0.03 sec)

SQl的分類

SQl結構化查詢語言包含6個部分

數據查詢語言（DQL（data query language）），作用從表中獲取數據，關鍵字select，
數據操作語言（DMl（data manipulation language））作用處理表中的數據insert ，update，delete
事務處理語言（TPL）關鍵字begin，commit和 rollback
數據控制語言（DCl）grant（授權）和revoke
數據定義語言（DDl）create和drop在數據庫中創建新表或刪除表 alter
指針控制語言（CCl） declare cursor， fetch into 和update where current用於對一個或多個表單獨行的操作

查看數據庫

show databases;或show database link ‘‘;或select database;

 1 mysql> show databases;
 2 +--------------------+
 3 | Database           |
 4 +--------------------+
 5 | information_schema |
 6 | mysql              |
 7 | performance_schema |
 8 | student            |
 9 | test               |
10 +--------------------+
11 8 rows in set (0.01 sec)

創建數據庫

命令語法：create database <數據庫名> 註意庫名字不能數字開頭

 1 mysql> create database king;
 2 Query OK, 1 row affected (0.01 sec)
 3 
 4 mysql> show databases;
 5 +--------------------+
 6 | Database           |
 7 +--------------------+
 8 | information_schema |
 9 | king               |
10 | mysql              |
11 | performance_schema |
12 | student            |
13 | test               |
14 +--------------------+
15 6 rows in set (0.01 sec)
16 
17 mysql> show create  database king\G
18 *************************** 1. row ***************************
19        Database: king
20 Create Database: CREATE DATABASE `king` /*!40100 DEFAULT CHARACTER SET utf8 */
21 1 row in set (0.00 sec)
22 
23 mysql>

創建一個指定字符集的數據庫

1 mysql> CREATE DATABASE db_name DEFAULT CHARACTER SET utf8 COLLATE utf8_general_ci; #紅色指定編碼，藍色校驗規則。
2 Query OK, 1 row affected (0.01 sec)

刪除數據庫

drop database <數據庫名字>

 1 mysql> drop database test;
 2 Query OK, 1 row affected (0.07 sec)
 3 
 4 mysql> show databases;
 5 +--------------------+
 6 | Database           |
 7 +--------------------+
 8 | information_schema |
 9 | king               |
10 | mysql              |
11 | performance_schema |
12 | student            |
13 +--------------------+
14 5 rows in set (0.01 sec)

連接數據庫

命令：use <數據庫名>相當於linux下的cd切換目錄的命令，use是切換數據庫

 1 mysql> use king;
 2 Database changed
 3 mysql> select database();   #查看當前的數據庫，帶（）相當於函數，
 4 +------------+
 5 | database() |
 6 +------------+
 7 | king       |
 8 +------------+
 9 1 row in set (0.00 sec)

查看數據庫

select database （）;相當於linux下的pwd

 1 mysql> select version();　　　　#查看當前的版本
 2 +-----------+
 3 | version() |
 4 +-----------+
 5 | 5.5.40    |
 6 +-----------+
 7 1 row in set (0.06 sec)
 8 mysql> select user();　　　　　　#查看當前的用戶
 9 +----------------+
10 | user()         |
11 +----------------+
12 | root@localhost |
13 +----------------+
14 1 row in set (0.04 sec)
15 mysql> select now();　　　　　　#查看當前的時間
16 +---------------------+
17 | now()               |
18 +---------------------+
19 | 2018-11-02 19:26:39 |
20 +---------------------+
21 1 row in set (0.02 sec)
22 mysql>

表操作

創建表並查看

create table <表名>（<字段名1><類型1>）;

 1 mysql> create table im(id int(3) not null, name varchar(20) not null default‘QQ‘　　　　#創建表id為int類型，name為varchar
 2 );
 3 Query OK, 0 rows affected (0.59 sec)
 4 mysql> show tables from king;　　　　　　　　　　　　　　#從king數據庫中查看表
 5 +----------------+
 6 | Tables_in_king |
 7 +----------------+
 8 | im |
 9 +----------------+
10 1 row in set (0.04 sec)
11 mysql> desc im;　　　　　　　　　　　　　　　　　　　　#查看表結構
12 +-------+-------------+------+-----+---------+-------+
13 | Field | Type | Null | Key | Default | Extra |
14 +-------+-------------+------+-----+---------+-------+
15 | id | int(3) | NO | | NULL | |
16 | name | varchar(20) | NO | | QQ | |
17 +-------+-------------+------+-----+---------+-------+
18 2 rows in set (0.22 sec)
19 mysql>

show colums from im;查看表結構

1 mysql> show create table im \G;　　　　　　　　#\G Send command to mysql server，display result vertically向MySQL服務器發送命令，垂直顯示結果
2 *************************** 1. row ***************************
3        Table: im
4 Create Table: CREATE TABLE `im` (
5   `id` int(3) NOT NULL,
6   `name` varchar(20) NOT NULL DEFAULT ‘QQ‘
7 ) ENGINE=InnoDB DEFAULT CHARSET=utf8
8 1 row in set (0.64 sec)

mysql表的字段類型

列類型	需要的存儲量
tinyint	1字節
smallint	2個字節
mediumint	3個字節
int	4個字節
integer	4個字節
bigint	8個字節
float（X）	4如果x<=24或8如果25<=X=53
float	4個字節
double	8個字節
double precision	8個字節
real	8個字節
decimal（M，D）	M字節（D+2，如果m<D）
numeric（M，D）	M字節（D+2，如果m<D）

為表的字段創建索引

創建主鍵索引，查詢數據庫，按主鍵查詢是最快的，每一個表只有一個主鍵列，但是可以有多個普通的索引列，主鍵列要求列的內容必須唯一，而索引列不要求內容必須唯一。

create table student(
id int (4) not null auto_increment,
name char(20) not null,
age tinyint(2) not null default‘0‘,
dept varchar(16) default null,
primary key (id),
key index_name(name));

1 mysql> create table student( id int (4) not null auto_increment, name char(20) n
2 ot null, age tinyint(2) not null default‘0‘,dept varchar(16) default null,primar
3 y key (id), key index_name(name));
4 Query OK, 0 rows affected (0.18 sec)

auto_increment自增，primary key (id), 主鍵，key index_name(name));普通索引，

 1 mysql> desc student;　　　　　　　　#查看創建的student表
 2 +-------+-------------+------+-----+---------+----------------+
 3 | Field | Type        | Null | Key | Default | Extra          |
 4 +-------+-------------+------+-----+---------+----------------+
 5 | id    | int(4)      | NO   | PRI | NULL    | auto_increment |
 6 | name  | char(20)    | NO   | MUL | NULL    |                |
 7 | age   | tinyint(2)  | NO   |     | 0       |                |
 8 | dept  | varchar(16) | YES  |     | NULL    |                |
 9 +-------+-------------+------+-----+---------+----------------+
10 4 rows in set (0.17 sec)

alter table student drop primary key ;　　　　　　刪除主鍵，測試不行，

1 mysql> alter table student drop  primary key ;
2 ERROR 1075 (42000): Incorrect table definition; there can be only one auto column and it must be defined as a key

　　　　　　　　　　　　　　　不正確的表定義；只能有一個自動COLUM它必須被定義為一個密鑰

alter table student change id id int primary key auto_increment; 如果創建表忘記添加主鍵了，就執行這個。

創建普通索引分為唯一索引和普通索引

alter table student drop index index_name; # index固定索引，index_name是你創建表的時候的索引

alter table student add index index_name（name）;

create index index_name on student （name（8））; # index固定索引（固定寫法），index_name 隨便寫但要見名知意， on student 在哪個表上（student）8就是前8個字符創建索引。

create index index_name_dept on student （name，dept）

按條件列查詢數據時，聯合索引是有前綴生效特性的 index（a，b，c）僅a，ab，abc三個查詢條件列可以走索引

查看表的索引

 1 mysql> show index from student\G;
 2 *************************** 1. row ***************************
 3         Table: student
 4    Non_unique: 0
 5      Key_name: PRIMARY
 6  Seq_in_index: 1
 7   Column_name: id
 8     Collation: A
 9   Cardinality: 0
10      Sub_part: NULL
11        Packed: NULL
12          Null:
13    Index_type: BTREE
14       Comment:
15 Index_comment:
16 *************************** 2. row ***************************
17         Table: student
18    Non_unique: 1
19      Key_name: index_name
20  Seq_in_index: 1
21   Column_name: name
22     Collation: A
23   Cardinality: 0
24      Sub_part: NULL
25        Packed: NULL
26          Null:
27    Index_type: BTREE
28       Comment:
29 Index_comment:
30 2 rows in set (0.00 sec)

創建唯一索引

create unique index uni on student（name）;

 1 mysql> create unique index uni on student (name);
 2 Query OK, 0 rows affected (0.09 sec)
 3 Records: 0  Duplicates: 0  Warnings: 0
 4 mysql> desc student;
 5 +-------+-------------+------+-----+---------+----------------+
 6 | Field | Type        | Null | Key | Default | Extra          |
 7 +-------+-------------+------+-----+---------+----------------+
 8 | id    | int(4)      | NO   | PRI | NULL    | auto_increment |
 9 | name  | char(20)    | NO   | UNI | NULL    |                |
10 | age   | tinyint(2)  | NO   |     | 0       |                |
11 | dept  | varchar(16) | YES  |     | NULL    |                |
12 +-------+-------------+------+-----+---------+----------------+
13 4 rows in set (0.02 sec)

要在表的列上創建索引
索引會加快查詢的速度，但是會影響更新的速度
索引不是越多越好，要在頻繁查詢的where後的條件列上創建索引
小表或唯一值極少的列上不建索引，要在帶包以及不同內容多的列上創建索引

往表中插入數據

create table test(

id int(4) not null auto_increment,

name char(20) not null,

primary key (id)

);

 1 mysql> create table test(id int(4) not null auto_increment, name char(20) not n
 2 ll,primary key (id));
 3 Query OK, 0 rows affected (0.01 sec)
 4 mysql> show tables;
 5 +----------------+
 6 | Tables_in_king |
 7 +----------------+
 8 | student        |
 9 | test           |
10 +----------------+
11 2 rows in set (0.00 sec)
12 mysql> insert into test (id,name) values(1,‘boy‘);  #插入數據，主鍵自增我們直接插name，insert into test（name） values（‘new‘）;
13 Query OK, 1 row affected (0.05 sec)
14 mysql> select *from test;
15 +----+------+
16 | id | name |
17 +----+------+
18 |  1 | boy  |
19 +----+------+
20 1 row in set (0.04 sec)

mysql> delete from test;
Query OK, 1 row affected (0.05 sec)
mysql> select *from test;
Empty set (0.00 sec)
mysql> insert into test (id,name) values(1,‘boy‘),(2,‘new‘);
Query OK, 2 rows affected (0.00 sec)
Records: 2  Duplicates: 0  Warnings: 0

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創建/查看/刪除mysql系統的用戶

語法：

create user ‘用戶名‘@‘主機名‘ identified by ‘用戶名‘;　　創建用戶
select host,user from mysql.user; 查看用戶
drop user 用戶名@‘%‘;註意可以是單或者雙引號，但不能不加，刪除用戶
delete from mysql.user where user=‘用戶名‘ and host=‘@後面指定的主機名’;

 1 mysql> create user ‘usrabc‘@‘%‘ identified by ‘usrabc‘;  #創建usrabc用戶
 2 Query OK, 0 rows affected (0.49 sec)
 3 mysql> select host,user from mysql.user;　　　　　　　　　#查看所有用戶　　　
 4 +-----------+--------+
 5 | host | user |
 6 +-----------+--------+
 7 | % | usrabc |
 8 | localhost | root |
 9 +-----------+--------+
10 2 rows in set (0.00 sec)
11 mysql> drop user usrabc@‘%‘;　　　　　　　　　　　　#刪除usrabc用戶
12 Query OK, 0 rows affected (0.00 sec)

處理完用戶最好刷新一下權限，flush privileges;

創建mysql用戶及賦予用戶權限

通過help grant 查看幫助，比較常用的創建用戶的方法是：CREATE USER ‘jeffrey‘@‘localhost‘ IDENTIFIED BY ‘mypass‘

CREATE USER ‘jeffrey‘@‘localhost‘ IDENTIFIED BY ‘mypass‘
GRANT ALL ON db1.* TO ‘jeffrey‘@‘localhost‘　　　　　　　　　　#這倆命令是先用create創建用戶，然後在授權
GRANT SELECT ON db2.invoice TO ‘jeffrey‘@‘localhost‘
GRANT USAGE ON *.* TO ‘jeffrey‘@‘localhost‘ WITH MAX_QUERIES_PER_HOUR 90

通過grant命令創建用戶並授權，命令語法：grant all privileges on dbname.* to username@localhost identified by ‘passwd‘;

grant	all privileges	on dbname.*	to username@localhost	identified by ‘passwd‘
授權命令	對應權限	目標：庫和表	用戶名和客戶端主機	用戶密碼

1 mysql> grant all privileges on king.* to liang@localhost identified by ‘123456‘;
2 #創建liang用戶，對king庫具備所有權限，允許從localhost主機登陸管理數據庫，密碼是123456.
3 Query OK, 0 rows affected (0.01 sec)
4 mysql> flush privileges;
5 Query OK, 0 rows affected (0.96 sec)

 1 mysql> show grants for liang@localhost;　　　　　　　　#查看權限
 2 +-------------------------------------------------------------------------------
 3 -------------------------------+
 4 | Grants for liang@localhost
 5                                |
 6 +-------------------------------------------------------------------------------
 7 -------------------------------+
 8 | GRANT USAGE ON *.* TO ‘liang‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74
 9 329105EE4568DDA7DC67ED2CA2AD9‘ |
10 | GRANT ALL PRIVILEGES ON `king`.* TO ‘liang‘@‘localhost‘
11                                |
12 +-------------------------------------------------------------------------------
13 -------------------------------+
14 2 rows in set (0.07 sec)

create和grant配合

1 mysql> create user zh@localhost identified by ‘123456‘;
2 Query OK, 0 rows affected (0.04 sec)
3 mysql> grant all on king.* to zh@localhost;
4 Query OK, 0 rows affected (0.00 sec)
5 mysql> flush privileges;
6 Query OK, 0 rows affected (0.00 sec)

授權局域網內主機遠程連接數據庫grant all privileges on king.* to [email protected].% identified by ‘123456‘;把localhost改為ip就可以了。連接，mysql -uliang -p123456 -h10.0.0.%

 1 mysql> show grants for zh@localhost;　　　　　　　　#查看zh用戶權限
 2 +-------------------------------------------------------------------------------
 3 ----------------------------+
 4 | Grants for zh@localhost
 5 |
 6 +-------------------------------------------------------------------------------
 7 ----------------------------+
 8 | GRANT USAGE ON *.* TO ‘zh‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329
 9 105EE4568DDA7DC67ED2CA2AD9‘ |
10 | GRANT ALL PRIVILEGES ON `king`.* TO ‘zh‘@‘localhost‘
11 |
12 +-------------------------------------------------------------------------------
13 ----------------------------+
14 2 rows in set (0.16 sec)
15 
16 mysql> revoke insert on king.* from zh@localhost;　　　　#更改權限
17 Query OK, 0 rows affected (0.04 sec)
18 
19 mysql> show grants for zh@localhost;
20 +-------------------------------------------------------------------------------
21 --------------------------------------------------------------------------------
22 -------------------------------------------------------------+
23 | Grants for zh@localhost
24 
25 |
26 +-------------------------------------------------------------------------------
27 --------------------------------------------------------------------------------
28 -------------------------------------------------------------+
29 | GRANT USAGE ON *.* TO ‘zh‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329
30 105EE4568DDA7DC67ED2CA2AD9‘
31 |
32 | GRANT SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE T
33 EMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, A
34 LTER ROUTINE, EVENT, TRIGGER ON `king`.* TO ‘zh‘@‘localhost‘ |
35 +-------------------------------------------------------------------------------
36 --------------------------------------------------------------------------------
37 -------------------------------------------------------------+
38 2 rows in set (0.06 sec)

1 mysql -uroot -p123456 -e "show grants for zh@localhost;"|grep -i grant　　#用linux中grep命令過濾需要的權限
2 Grants for zh@localhost
3 GRANT USAGE ON *.* TO ‘zh‘@‘localhost‘ IDENTIFIED BY PASSWORD ‘*6BB4837EB74329
4 105EE4568DDA7DC67ED2CA2AD9‘
5 GRANT SELECT, UPDATE, DELETE, CREATE, DROP, REFERENCES, INDEX, ALTER, CREATE T
6 EMPORARY TABLES, LOCK TABLES, EXECUTE, CREATE VIEW, SHOW VIEW, CREATE ROUTINE, A
7 LTER ROUTINE, EVENT, TRIGGER ON `king`.* TO ‘zh‘@‘localhost‘

查看mysql的ALL PRIVILEGES權限mysql -uroot -p123456 -e "show grants for zh@localhost;"|grep -i grant|tail -1|tr ‘，’ ‘\n’ >a.txt

我們在授權用戶最小的滿足業務需求的權限，而不是一味的授權ALl PRIVILEGES。

MySQL常用命令基礎操作

host isp 創建表 fin err name p12 就是 local MySQL啟動與更改密碼 mysql啟動基本原理說明： /etc/init.d/mysqld是一個shell啟動腳本，啟動後最終會調用，mysqld_safe腳本，最後調用mysqld服務啟動

MySQL常用命令基礎操作

MySQL啟動與更改密碼

mysql啟動基本原理說明：

關閉mysql

登陸mysql

更改root密碼

單實例mysql修改丟失root方法

多實例mysql修改丟失root方法

SQl的分類

查看數據庫

創建數據庫

刪除數據庫

連接數據庫

查看數據庫

表操作

創建表並查看

mysql表的字段類型

為表的字段創建索引

查看表的索引

創建唯一索引

往表中插入數據

創建/查看/刪除mysql系統的用戶

創建mysql用戶及賦予用戶權限

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