数据库 MySql

常用sql语句整理：mysql

"Common sql statement"

Posted by 吴庆宝 on November 29, 2018

Mysql基础

mysql安装

yum安装

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# 检测已安装的mysql
yum list installed | grep mysql

# 移除已安装的mysql
yum -y remove mysql-libs.x86_64

# 下载mysql5.7的rpm包
wget https://dev.mysql.com/get/mysql57-community-release-el6-11.noarch.rpm

# yum本地安装源
yum localinstall mysql57-community-release-el6-11.noarch.rpm

# 检测允许安装的mysql插件
yum repolist enabled | grep mysql
yum search mysql-community

# 安装mysql
yum -y install mysql-community-server.x86_64

# 启动mysql
service mysqld start

# 自启动
chkconfig mysqld on

# 初始密码
-> 2lNu<K?kk;6%
grep 'temporary password' /var/log/mysqld.log

# 进入数据库
mysql -u root -p 2lNu<K?kk;6%

# 修改密码
ALTER USER 'root'@'localhost' IDENTIFIED BY 'Root666,.';

# 远程登录密码
GRANT ALL ON *.* to root@'%' IDENTIFIED BY 'Root666,.';
GRANT ALL ON *.* to shengj@'%' IDENTIFIED BY 'Root666,.';

# 远程登录
mysql -h 104.223.3.138  -u root  -p Root666,.

数据库

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# 创建数据库
create database `demo`;

# 查看所有数据库
show databases;

# 查看某个数据库
show create database `demo`;

# 修改数据库编码
alter database `demo` default character set utf8 collate utf8_unicode_ci;

# 删除数据库
drop database `demo`;

常用sql语句整理：mysql

1.增

  • 增加一张表 
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    CREATE TABLE `table_name`(
...
)ENGINE=InnoDB DEFAULT CHARSET=utf8;
  • 增加记录 
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    INSERT INTO `your_table_name`(`column_name`)
VALUES
('your_value_one'),
('your_value_two');
  • 增加字段 
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    ALTER TABLE `your_table_name`
ADD `your_column_name` ...
AFTER `column_name`;
  • 增加索引
    • 主键 
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      ALTER TABLE `your_table_name`
ADD PRIMARY KEY your_index_name(your_column_name);
    • 唯一索引 
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      ALTER TABLE `your_table_name`
ADD UNIQUE your_index_name(your_column_name);
    • 普通索引 
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      ALTER TABLE `your_table_name`
ADD INDEX your_index_name(your_column_name);
    • 全文索引 
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      ALTER TABLE `your_table_name`
ADD FULLTEXT your_index_name(your_column_name);

2.删

  • 逐行删除 
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2

    DELETE FORM `table_name`
WHERE ...;
  • 清空整张表 
    1

    TRUNCATE TABLE `your_table_name`;
  • 删除表 
    1

    DROP TABLE `your_table_name`;
  • 删除字段 
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    ALTER TABLE `your_table_name`
DROP `column_name`;
  • 删除索引 
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    ALTER TABLE `your_table_name`
DROP INDEX your_index_name(your_column_name);

3.改

  • 变更数据 
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    UPDATE `table_name`
SET column_name=your_value
WHERE ...;
  • 变更字段 
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    ALTER TABLE `your_table_name`
CHANGE `your_column_name` `your_column_name` ...(变更);
  • 变更字段值为另一张表的某个值 
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    UPDATE `your_table_name`
AS a
JOIN `your_anther_table_name`
AS b
SET a.column = b.anther_column
WHERE a.id = b.a_id...;

4.查

  • 普通查询 
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    SELECT `column_name_one`, `column_name_two`
FROM `table_name`;
  • where条件查询 
    1

    select * from `user` where id=1;
  • in/not in 关键字查询 
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    select * from `user` where id in (1,2);
select * from `user` where id not in (1,2);
  • between and 关键字查询 
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    select * from `user` where id between 1 and 3;
  • 空值(null)查询，使用is null来判断 
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    alter table `user` add `age` varchar(10) default null;
select * from `user` where age is null;
  • distinct(去重)关键字查询 
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    select distinct(account) from `user`;
  • like关键字查询 
    1

    select * from `user` where `account` like "%en%";
  • and关键字多条件查询,or关键字的使用也是类似 
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    select * from `user` where `account`='shengj' and `id`>1;
select * from `user` where `account`='shengj' or  `account`='cenh';

聚合函数

count()函数 -> 记录总条数

sum()函数 -> 某个字段的总和

avg()函数 -> 字段的平均数

max()函数 -> 字段的最大值

min()函数 -> 字段的最小值

  • 排序 order by 
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    select * from `user` order by `id` desc; // 倒序
select * from `user` order by `id` asc; // 升序 默认
  • 分组 group by 
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    select * from `user` group by `id`;
  • 使用limit限制查询结果的数量 
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    select * from `user` limit 2;
  • 别名 as 
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    select u.id from `user` as u; // 表别名
select account as name from `user`; // 字段别名
  • 关联查询 
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    SELECT *
FROM `your_table_name`
AS a
JOIN `your_anther_table_name`
AS b
WHERE a.column_name = b.column_name...;
  • 合计函数条件查询：WHERE 关键字无法与合计函数一起使用 
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    SELECT aggregate_function(column_name)
FROM your_table_name
GROUP BY column_name
HAVING aggregate_function(column_name)...;
  • 同一个实例下跨库查询 
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    SELECT *
FROM database_name.your_table_name
AS a
JOIN another_database_name.your_another_table_name
AS b
WHERE a.column_name = b.column_name...;

5.复制一张表结构

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CREATE TABLE `your_table_name`
LIKE `destination_table_name`;

6.完全复制一张表：表结构+全部数据

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CREATE TABLE `your_table_name`
LIKE `destination_table_name`;

INSERT INTO `your_table_name`
SELECT *
FROM `destination_table_name`;

附录：mysql命令

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登陆：mysql -h host -u username -p
列出数据库：SHOW DATABESES;
列出表:SHOW TABLES;
列出表结构:DESC table_name
使用一个数据库：USE database_name;
导入：source 'file';
导出：mysqldump -h 127.0.0.1 -u root -p "database_name" "table_name" --where="condition" > file_name.sql;
查看慢日志：mysqldumpslow -s [c:按记录次数排序/t:时间/l:锁定时间/r:返回的记录数] -t [n:前n条数据] -g "正则"　/path
新增用户： insert into `user`(`Host`, `User`, `authentication_string`) value('localhost', 'username', password('pwd'))

mysql 5.7 新增用户

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// 插入新用户
insert into mysql.user(Host, User, authentication_string, ssl_cipher, x509_issuer, x509_subject
value('localhost', 'username', password('password'), '', '', '');

// 数据库授权
grant all privileges on dbname.name.* to username@localhost identified by 'password';

// 刷新权限信息
FLUSH PRIVILEGES;
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