centos7下安装mysql5.7

1.官网找到 https://dev.mysql.com/downloads/repo/yum/

2.wget https://repo.mysql.com/mysql80-community-release-el7-3.noarch.rpm

rpm -ivh mysql80-community-release-el7-3.noarch.rpm

若果报错误：warning: mysql80-community-release-el8-1.noarch.rpm: Header V3 DSA/SHA1 Signature, key ID 5072e1f5: NOKEY

解决：rpm --import /etc/pki/rpm-gpg/RPM*

重新  rpm -ivh mysql80-community-release-el7-3.noarch.rpm

说明：虽然下载的源文件名字为mysql80-community-release-el7-3.noarch.rpm，不用担心，里边其实是包含了我们所要装的版本

yum repolist all | grep mysql 

可以看到，默认的安装源为mysql80-community版本

配置默认源5.7

使用yum-config-manager --disable mysql80-community来取消mysql80-community的默认安装，然后

使用yum-config-manager --enable mysql57-community来使能mysql57-community成为yum默认安装版本。

安装

执行安装命令：

yum install mysql-community-server

yum -y install mysql-devel

启动mysql服务

systemctl restart mysqld.service //重启mysql服务

systemctl status mysqld.service //查看mysql状态

systemctl stop mysqld.service //停止mysql服务
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获取临时密码

临时密码存在/var/log/mysqld.log中，使用如下命令查看：

grep "temporary password" /var/log/mysqld.log

登陆mysql

mysql -u root -p

Enter password:

进入mysql > update user set authentication_string = password('root') where user='root'; 后面跟分号 密码策略：大小写字母+数字+特殊符号

也可忽略验证：

vim /etc/my.cnf

增加 

skip-grant-tables 忽略验证  保存，重新运行mysql  mysql -u root -p  直接enter 进入不用输入密码 
修改用户密码：
update user set authentication_string = password('root') where user='root'; 
root 登录后
一定要修改密码

      alter user 'root'@'localhost' identified by 'test';

然后就可以了。

# For advice on how to change settings please see
# http://dev.mysql.com/doc/refman/5.7/en/server-configuration-defaults.html

[mysqld]
#skip-grant-tables
#
# Remove leading # and set to the amount of RAM for the most important data
# cache in MySQL. Start at 70% of total RAM for dedicated server, else 10%.
# innodb_buffer_pool_size = 128M
#
# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin
#
# Remove leading # to set options mainly useful for reporting servers.
# The server defaults are faster for transactions and fast SELECTs.
# Adjust sizes as needed, experiment to find the optimal values.
# join_buffer_size = 128M
# sort_buffer_size = 2M
# read_rnd_buffer_size = 2M
datadir=/data/mysql
#socket=/var/lib/mysql/mysql.sock
socket=/data/mysql/mysql.sock

# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0

log-error=/var/log/mysqld.log
pid-file=/var/run/mysqld/mysqld.pid

更改用户权限增加用户

1.创建新用户的SQL语句：

CREATE USER ‘pig‘@‘192.168.1.101_‘ IDENDIFIED BY ‘123456‘;

// pig 是用户名，@后面的是指定ip(如果不限制只能在某个ip，@后面改为‘%’),by后面的是 密码

2.设置这个用户的权限，使用GRANT语句

(如限制某个用户只能查询，不能修改，或者限定只能查询特定的表)

语法：

mysql> grant 权限1,权限2,...权限n on 数据库名称.表名称 to 用户名@用户地址 identified by ‘连接口令‘;

可选的权限列表：select, insert, update, delete, create, drop,

index, alter, grant, references, reload,

shutdown, process, file等14个权限

eg:

1. mysql> grant select,insert,update,delete,create,drop on vtdc.employee to joe@10.163.225.87 identified by ‘123‘;

给来自10.163.225.87的用户joe分配可对数据库vtdc的employee表

进行select,insert,update,delete,create,drop等操作的权限，并设定口令为123。

2. mysql>grant all privileges on vtdc.* to joe@10.163.225.87 identified by ‘123‘;

给来自10.163.225.87的用户joe分配可对数据库vtdc所有表进行所有操作的权限，并设定口令为123。

3. mysql>grant all privileges on *.* to joe@10.163.225.87 identified by ‘123‘;

给来自10.163.225.87的用户joe分配可对所有数据库的所有表进行所有操作的权限，并设定口令为123。

4. mysql>grant all privileges on *.* to joe@localhost identified by ‘123‘;

给本机用户joe分配可对所有数据库的所有表进行所有操作的权限，并设定口令为123。

5. mysql>flush privileges; //刷新系统权限表

use mysql  

show databases;(显示db)

show tables;显示表

describe test; 或者show columns from test；显示表结构

drop table test;删除表

create table test( id int not null auto_increment primary key, title varchar(100) not null, name varchar(50) not null, age int not null, createtime datetime not null); 创建表

insert into test(title,name,age,createtime) values ('11','222',11,'2021-09-09'); 添加数据

update test set title='876868' where id =1;  修改数据

delete from test where id=1;  删除数据

select * from test order by id asc; 排序