一、centos7 中安装 mysql 8.x

1、下载安装包

wget https://downloads.mysql.com/archives/get/p/23/file/mysql-8.0.33-1.el7.x86_64.rpm-bundle.tar

2、解压

tar -zxvf mysql-8.0.33-1.el7.x86_64.rpm-bundle.tar

3、卸载mariodb

yum remove -y *mariadb*

4、依次安装依赖包（libs，client，common，server）

yum -y install mysql-community-common-8.0.33-1.el7.x86_64.rpm

yum install mysql-community-client-8.0.33-1.el7.x86_64.rpm 
yum install mysql-community-libs-8.0.33-1.el7.x86_64.rpm

yum install -y mysql-community-server-8.0.33-1.el7.x86_64.rpm

5、初始化配置mysqlh

vim /etc/my.cnf

[mysqld]
explicit_defaults_for_timestamp=tree

mysqld -initialize

6、启动mysql服务

systemctl start mysqld

systemctl enable mysqld      #开机启动mysql服务

7、获得初始密码

cat /var/log/mysqld.log|grep password

8、初始密码登陆

mysql -uroot -p Zhang@2002

9、设置密码

ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY 'Zhang@2002';

二、数据库操作

1、数据库对象
2、数据库的操作
1.数据库系统         DBMS
2.数据库         DB
3.表         table
4.记录         record
5.字段         feild
（1）查看数据库

select host,user from mysql,user;

show databases;

（2）创建库

mysql> create datababse test charset utf8;
Query OK, 1 row affected, 1 warning (0.01 sec)
mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
| test |
+--------------------+
5 rows in set (0.00 sec)

（3）查看库

mysql> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| sys |
+--------------------+
4 rows in set (0.01 sec)

3、表的操作
（1）选择表

mysql> use mysql;
Reading table information for completion of table and
column names
You can turn off this feature to get a quicker startup
with -A
Database changed

（2）查看表

mysql> show tables;
+------------------------------------------------------+
| Tables_in_mysql |
+------------------------------------------------------+
| columns_priv |
| component |
| db |
| default_roles |
| engine_cost |
| func |
| general_log |
| global_grants |
| gtid_executed |
| help_category |
| help_keyword |
| help_relation |
| help_topic |
| innodb_index_stats |
| innodb_table_stats |
| ndb_binlog_index |
| password_history |
| plugin |
| procs_priv |
| proxies_priv |
| replication_asynchronous_connection_failover |
| replication_asynchronous_connection_failover_managed |
| replication_group_configuration_version |
| replication_group_member_actions |
| role_edges |
| server_cost |
| 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 |
+------------------------------------------------------+
38 rows in set (0.01 sec)

（3）创建表

mysql> CREATE TABLE `test`.`user` (
-> `id` INT NOT NULL AUTO_INCREMENT,
-> `username` VARCHAR(45) NOT NULL,
-> `password` VARCHAR(45) NOT NULL,
-> PRIMARY KEY (`id`),
-> UNIQUE INDEX `username_UNIQUE` (`username` ASC)
VISIBLE)
-> COMMENT = 'us';
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| user           |
| user0          |
+----------------+

（4）删除表

mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| user |
| user0 |
+----------------+
2 rows in set (0.00 sec)
mysql> drop table user0;
Query OK, 0 rows affected (0.01 sec)
mysql> show tables;
+----------------+
| Tables_in_test |
+----------------+
| user |
+----------------+
1 row in set (0.01 sec)

新增列

ALTER TABLE `test`.`user`
ADD COLUMN `realname` VARCHAR(45) NULL AFTER `password`;
mysql> desc user;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar(45) | NO | UNI | NULL |
|
| password | varchar(45) | NO | | NULL |
|
| realname | varchar(45) | YES | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+
4 rows in set (0.01 sec)

        修改列名

mysql> ALTER TABLE `test`.`user`
-> CHANGE COLUMN `realname` `zsxm` VARCHAR(45) NULL
DEFAULT NULL ;
Query OK, 0 rows affected (0.02 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc user;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar(45) | NO | UNI | NULL |
|
| password | varchar(45) | NO | | NULL |
|
| zsxm | varchar(45) | YES | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+

        删除列

mysql> ALTER TABLE `test`.`user`
-> DROP COLUMN `zsxm`;
Query OK, 0 rows affected (0.01 sec)
Records: 0 Duplicates: 0 Warnings: 0
mysql> desc user;
+----------+-------------+------+-----+---------+---------
-------+
| Field | Type | Null | Key | Default | Extra
|
+----------+-------------+------+-----+---------+---------
-------+
| id | int | NO | PRI | NULL |
auto_increment |
| username | varchar(45) | NO | UNI | NULL |
|
| password | varchar(45) | NO | | NULL |
|
+----------+-------------+------+-----+---------+---------
-------+
3 rows in set (0.00 sec)

4、记录的操作
（1）新增
insert into 表名（字段名列表） values （字段值列表）

（2）删除
delete from user where 条件

（3）修改

zhangsan的密码修改为123