mysql基础操作

Posted 2021-01-11 爱折腾才能更好的折腾

mysql相关操作

 

一、库操作

1、查看当前在哪个库

select database();

+------------+
| database() |
+------------+
| userinfo       |
+------------+

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2、创建库

create database 库名 default character set=字符集;     # 此处如果不指定，则使用系统默认字符集

mysql> create database userinfo default character set=utf8mb4;
Query OK, 1 row affected
mysql> show create database userinfo;
+----------+----------------------------------------------------------------------+
| Database | Create Database                                                      |
+----------+----------------------------------------------------------------------+
| userinfo | CREATE DATABASE `userinfo` /*!40100 DEFAULT CHARACTER SET utf8mb4 */ |
+----------+----------------------------------------------------------------------+

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3、查看当前系统所有库

show databases;

+--------------------+
| Database           |
+--------------------+
| information_schema |
| info               |
| mysql              |
| performance_schema |
| test               |
| userinfo           |
+--------------------+

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4、使用库

use 库名;

5、删除库

drop database 库名;                # 此操作很危险，删除库的同时删除库下的所有表

二、数据类型

1 、数值型

\'\'\'
unsigned:表示无符号的  只针对数值型
float(M,D) 浮点型
decimal(M,D) 定点型  比float更加准确  `money` decimal(10,2) NOT NULL DEFAULT \'0.00\' COMMENT \'充值金额\',
M:精度(总位数)  D:标度(小数位)
\'\'\'

2、 字符串类型

 

3、 时间类型

 4、 特殊的NULL类型

\'\'\'
NULL不是假，也不是真，而是空
NULL的判断只能用is null， is not null
NULL影响查询速度，一般避免其值为NULL
\'\'\'

三、表操作

1、查看当前数据库中所有表

show full tables;

mysql> show tables;
+---------------------------+
| Tables_in_mysql           |
+---------------------------+
| columns_priv              |
| db                        |
| event                     |
| func                      |
| general_log               |
| help_category             |
| help_keyword              |
| help_relation             |
| help_topic                |
| innodb_index_stats        |
| innodb_table_stats        |
| ndb_binlog_index          |
| plugin                    |
| proc                      |
| procs_priv                |
| proxies_priv              |
| 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                      |
+---------------------------+

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2、创建表

create table student(
id int not null auto_increment primary key,
name varchar(10) character set utf8mb4  not null default \'\' comment \'姓名\'
) default character set=\'utf8mb4\';

# auto_increment  自增 
# default \'\' 默认是空
# comment \'注释\'
# primary key 主键   一种特殊的唯一索引，不允许有空值，如果主键使用单个列，则它的值必须唯一，如果是多列，则其组合必须唯一

3、修改表名

alter table current_table_name rename to new_table_name;

mysql> alter table student rename to accountinfo;
Query OK, 0 rows affected

mysql> show tables;
+--------------------+
| Tables_in_userinfo |
+--------------------+
| accountinfo        |
+--------------------+
1 row in set

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3、清空表

3.1  delete from 表名;           # delete 清空表，如果遇到自增列，会从delete前最后一行的自增列开始计数

mysql> select * from accountinfo;
+----+-------+
| id | name  |
+----+-------+
|  1 | li    |
|  2 | fred  |
|  3 | fred2 |
|  4 | fred3 |
|  5 | fred4 |
+----+-------+
5 rows in set

mysql> delete from accountinfo;
Query OK, 5 rows affected

mysql> insert into accountinfo(name) values(\'fred4\');
Query OK, 1 row affected

mysql> select * from accountinfo;
+----+-------+
| id | name  |
+----+-------+
|  6 | fred4 |
+----+-------+
1 row in set

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3.2  truncate table 表名;         #  truncate 清空表  如果遇到自增列，会从头开始   

mysql> truncate table
 accountinfo;
Query OK, 0 rows affected

mysql> insert into accountinfo(name) values(\'fred4\');
Query OK, 1 row affected

mysql> insert into accountinfo(name) values(\'fred4\');
Query OK, 1 row affected

mysql> select * from accountinfo;
+----+-------+
| id | name  |
+----+-------+
|  1 | fred4 |
|  2 | fred4 |
+----+-------+
2 rows in set

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4、删除表

drop table 表名;

5、修改表

5.1 添加字段

alter table student add 字段名 tinyint(4) not null default \'0\' comment \'地址\';      # 默认是add到表的最后一列

 alter table student add phone int(11) not null default \'0\' comment \'电话\' after `name`;               # 在指定字段后面添加

mysql> alter table student add addr tinyint(4) not null default \'0\' comment \'地址
\';
Query OK, 0 rows affected
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
| addr  | tinyint(4)  | NO   |     | 0       |                |
+-------+-------------+------+-----+---------+----------------+
4 rows in set

mysql> alter table student add phone int(11) not null default \'0\' comment \'电话\' after `name`;
Query OK, 0 rows affected
Records: 0  Duplicates: 0  Warnings: 0

mysql> 
mysql> 
mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
| addr  | tinyint(4)  | NO   |     | 0       |                |
+-------+-------------+------+-----+---------+----------------+
5 rows in set

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5.2 修改字段

alter table student modify addr varchar(32) not null default \'\' comment \'地址\';

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
| addr  | tinyint(4)  | NO   |     | 0       |                |
+-------+-------------+------+-----+---------+----------------+

mysql> alter table student modify addr varchar(32) not null default \'\' comment \'地址\';
Query OK, 0 rows affected
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
| addr  | varchar(32) | NO   |     |         |                |
+-------+-------------+------+-----+---------+----------------+
5 rows in set

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5.3 删除字段

alter table student drop addr; 

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
| addr  | varchar(32) | NO   |     |         |                |
+-------+-------------+------+-----+---------+----------------+
5 rows in set

mysql> alter table student drop addr;
Query OK, 0 rows affected
Records: 0  Duplicates: 0  Warnings: 0

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
+-------+-------------+------+-----+---------+----------------+
4 rows in set

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 四、表数据的增删改

1、增加数据  insert into 

1.1 按规矩指定所有列名，并且每列都插入数据 insert into table_name(字段1，字段2,....)  values(值1,值2,....)       # 注意此处字段和值必须一一对应

insert into account(user_id,game_id,open_id,union_id,access_token) values(729672,7296723,\'oY8lLwjg3jVc\',\'oAxDHvxOabV\',\'14_KV2LYNVY7Ak0d\');

 1.2 对表中所有列插入数据，table_name后可以不用跟字段名 insert into table_name  values(值1,值2......)           # 此处表中有几个字段，必须对应几个值

insert into account  values(729672,7296723,\'oY8lLwjg3jVc\',\'oAxDHvxOabV\',\'14_KV2LYNVY7Ak0d\');

 

1.3  表中如果有字段是自增的，insert时，可以不用指定此列

insert into student(name,phone,sex) values(\'fred\',\'187\',\'2\');

mysql> desc student;
+-------+-------------+------+-----+---------+----------------+
| Field | Type        | Null | Key | Default | Extra          |
+-------+-------------+------+-----+---------+----------------+
| id    | int(11)     | NO   | PRI | NULL    | auto_increment |
| name  | varchar(10) | NO   |     |         |                |
| phone | int(11)     | NO   |     | 0       |                |
| sex   | tinyint(4)  | NO   |     | 0       |                |
+-------+-------------+------+-----+---------+----------------+
4 rows in set

mysql> insert into student(name,phone,sex) values(\'fred\',\'187\',\'2\');
Query OK, 1 row affected

mysql> select * from student;
+----+------+-------+-----+
| id | name | phone | sex |
+----+------+-------+-----+
|  1 | fred |   187 |   2 |
+----+------+-------+-----+
1 row in set

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1.4 将其他表中的的数据插入到指定表  insert into table_name(字段1,字段2..)  select  from  table_name1 

insert into guild_member(user_id,guild_id) select user_id,687490 from accountinfo limit 5;

mysql> desc guild_member;
+------------+---------------------+------+-----+-------------------+-------+
| Field      | Type                | Null | Key | Default           | Extra |
+------------+---------------------+------+-----+-------------------+-------+
| user_id    | int(11) unsigned    | NO   | PRI | NULL              |       |
| guild_id   | int(11) unsigned    | NO   | PRI | NULL              |       |
| admin      | tinyint(4)          | NO   |     | 0                 |       |
| is_union   | tinyint(4) unsigned | NO   |     | 0                 |       |
| score      | int(11)             | NO   |     | 0                 |       |
| win        | int(11)             | NO   |     | 0                 |       |
| s100       | int(11)             | NO   |     | 0                 |       |
| s300       | int(11)             | NO   |     | 0                 |       |
| s500       | int(11)             | NO   |     | 0                 |       |
| join_time  | timestamp           | NO   |     | CURRENT_TIMESTAMP |       |
| guild_data | varchar(2048)       | NO   |     |                   |       |
+------------+---------------------+------+-----+-------------------+-------+
11 rows in set (0.01 sec)

mysql> insert into guild_member(user_id,guild_id) select user_id,687490 from accountinfo limit 5;
Query OK, 5 rows affected (0.01 sec)
Records: 5  Duplicates: 0  Warnings: 0

mysql> select * from guild_member where guild_id=687490;
+---------+----------+-------+----------+-------+-----+------+------+------+---------------------+------------+
| user_id | guild_id | admin | is_union | score | win | s100 | s300 | s500 | join_time           | guild_data |
+---------+----------+-------+----------+-------+-----+------+------+------+---------------------+------------+
|  279899 |   687490 |     0 |        0 |     0 |   0 |    0 |    0 |    0 | 2018-10-09 16:17:02 |            |
|  321714 |   687490 |     0 |        0 |     0 |   0 |    0 |    0 |    0 | 2018-10-09 16:17:02 |            |
|  611391 |   687490 |     0 |        0 |     0 |   0 |    0 |    0 |    0 | 2018-10-09 16:17:02 |            |
|  961411 |   687490 |     0 |        0 |     0 |   0 |    0 |    0 |    0 | 2018-10-09 16:17:02 |            |
|  994470 |   687490 |     0 |        0 |     0 |   0 |    0 |    0 |    0 | 2018-10-09 16:17:02 |            |
+---------+----------+-------+----------+-------+-----+------+------+------+---------------------+------------+

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2、修改数据 update   table_name set  字段1=values；     # 注意 线上数据最好不要update   如果非要update  必须加where 条件

update accountinfo set room_card=room_card-10000 where user_id=729672;      # 如果不加where条件，表中这个列都会被修改，很危险

mysql> select user_id,nick,room_card from accountinfo where user_id=729672; 
+---------+--------------+-----------+
| user_id | nick         | room_card |
+---------+--------------+-----------+
|  729672 | 随梦而飞     |     11108 |
+---------+--------------+-----------+
1 row in set (0.00 sec)

mysql> update accountinfo set room_card=room_card-10000 where user_id=729672;
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select user_id,nick,room_card from accountinfo where user_id=729672;  
+---------+--------------+-----------+
| user_id | nick         | room_card |
+---------+--------------+-----------+
|  729672 | 随梦而飞     |      1108 |
+---------+--------------+-----------+
1 row in set (0.00 sec)

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update accountinfo set room_card=room_card-10000,nick=\'碎梦\' where user_id=729672;        # 同时修改多列 

mysql> select user_id,nick,room_card from accountinfo where user_id=729672;  
+---------+--------------+-----------+
| user_id | nick         | room_card |
+---------+--------------+-----------+
|  729672 | 随梦而飞     |      1108 |
+---------+--------------+-----------+
1 row in set (0.00 sec)

mysql> update accountinfo set room_card=room_card-10000,nick=\'碎梦\' where user_id=729672;       
Query OK, 1 row affected (0.00 sec)
Rows matched: 1  Changed: 1  Warnings: 0

mysql> select user_id,nick,room_card from accountinfo where user_id=729672;                
+---------+--------+-----------+
| user_id | nick   | room_card |
+---------+--------+-----------+
|  729672 | 碎梦   |     -8892 |
+---------+--------+-----------+
1 row in set (0.00 sec)

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3、删除数据(最好不要，可以用update一个标记字段代替，还可以实现sql审计)

delete from accountinfo where user_id=729672;

PS: mysql -U 阻止update 或 delete 不加条件执行     -U, --safe-updates  Only allow UPDATE and DELETE that uses keys.   加-U后，update和delete where条件的值结果必须唯一

否则会报1175的错误，key值不唯一

 

mysql> delete from account where user_id=102607;
ERROR 1175 (HY000): You are using safe update mode and you tried to update a table without a WHERE that uses a KEY column
mysql> select *  from account where user_id=102607;
+---------+---------+------------+----------+--------------+
| user_id | game_id | open_id    | union_id | access_token |
+---------+---------+------------+----------+--------------+
|  102607 | 1026075 | 1524023526 | visitor  | visitor      |
|  102607 | 1026075 | 1524023526 | visitor  | visitor      |
+---------+---------+------------+----------+--------------+
2 rows in set (0.00 sec)

where条件值不唯一，报错

 五、用户管理

1、查看指定用户的权限

show grants for root@\'172.16.16.%\';

mysql> show grants for root@\'172.16.16.%\';   
+-----------------------------------------------------+
| Grants for root@172.16.16.%                         |
+-----------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO \'root\'@\'172.16.16.%\' |
+-----------------------------------------------------+
1 row in set (0.00 sec)

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2、查看当前所有用户

select user,host from mysql.user;

mysql> select user,host from mysql.user;
+------+-----------+
| user | host      |
+------+-----------+
| root | 127.0.0.1 |
| root | ::1       |
|      | localhost |
| root | localhost |
+------+-----------+

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3、创建用户并授权

grant 权限 on 库.表 to user@\'host\' identified by \'明文密码\';

mysql> grant all on *.* to fred@\'127.0.0.1\' identified by \'835y1354\';
Query OK, 0 rows affected

mysql> flush privileges;
Query OK, 0 rows affected

mysql> 
mysql> show grants for fred@\'127.0.0.1\';
+----------------------------------------------------------------------------------------------------------------------+
| Grants for fred@127.0.0.1                                                                                            |
+----------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO \'fred\'@\'127.0.0.1\' IDENTIFIED BY PASSWORD \'*7DF241C2E2C1916417BD7B281C55FF4084F66C35\' |
+----------------------------------------------------------------------------------------------------------------------+
1 row in set

grant all on *.* to fred@\'127.0.0.1\' identified by \'835y1354\';

flush privileges;   强制刷新到权限表

4、修改已存在账号的密码

set password for \'user\'@\'host \' = password(\'明文密码\');

mysql> set password for \'fred\'@\'127 \' = password(\'ko2K24Cjga\');
1133 - Can\'t find any matching row in the user table
mysql> set password for \'fred\'@\'127.0.0.1\' = password(\'ko2K24Cjga\');
Query OK, 0 rows affected

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5、创建并授权超级管理员账号

grant all on *.* to fred_li@\'127.0.0.1\' identified by \'835y1354\' with grant option;

mysql> grant all on *.* to fred_li@\'127.0.0.1\' identified by \'835y1354\' with grant option;
Query OK, 0 rows affected

mysql> show grants for fred_li@\'127.0.0.1\';
+-------------------------------------------------------------------------------------------------------------------------------------------+
| Grants for fred_li@127.0.0.1                                                                                                              |
+-------------------------------------------------------------------------------------------------------------------------------------------+
| GRANT ALL PRIVILEGES ON *.* TO \'fred_li\'@\'127.0.0.1\' IDENTIFIED BY PASSWORD \'*7DF241C2E2C1916417BD7B281C55FF4084F66C35\' WITH GRANT OPTION |
+---------------------------

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6、查看当前登录的用户

select user();

mysql> select user();
+--------------------+
| user()             |
+--------------------+
| root@172.16.16.247 |
+--------------------+
1 row in set (0.00 sec)

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