macOS下用brew安装mysql

首先安装brew

macOS安装brew

使用brew安装mysql5.7

brew install mysql@5.7       （能够指定版本安装，不指定版本默认最新版本）

运行brew service start mysql 能够后台启动mysql
运行mysql.server start 前台启动mysql(关闭控制台，服务中止)

其中运行mysql_secure_installation 能够设置密码（如何想设置root这种4位的简单密码，系统默认是不容许的，须要修改两个参数，请看下面）

$ mysql_secure_installation

Securing the MySQL server deployment.

Connecting to MySQL using a blank password.

VALIDATE PASSWORD PLUGIN can be used to test passwords
and improve security. It checks the strength of password
and allows the users to set only those passwords which are
secure enough. Would you like to setup VALIDATE PASSWORD plugin?
// 提示是否设置密码
Press y|Y for Yes, any other key for No: y
// 提示选择密码强度等级
There are three levels of password validation policy:

LOW    Length >= 8
MEDIUM Length >= 8, numeric, mixed case, and special characters
STRONG Length >= 8, numeric, mixed case, special characters and dictionary                  file

Please enter 0 = LOW, 1 = MEDIUM and 2 = STRONG: 0
Please set the password for root here.
// 按照所选的密码强度要求设定密码
New password: 

Re-enter new password: 

// 提示密码强度50,不符合要求从新设置密码
Estimated strength of the password: 50 
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : y
 ... Failed! Error: Your password does not satisfy the current policy requirements

New password: 

Re-enter new password: 
// 提示密码强度100,符合要求继续进行
Estimated strength of the password: 100 
Do you wish to continue with the password provided?(Press y|Y for Yes, any other key for No) : y
By default, a MySQL installation has an anonymous user,
allowing anyone to log into MySQL without having to have
a user account created for them. This is intended only for
testing, and to make the installation go a bit smoother.
You should remove them before moving into a production
environment.
// 提示删除默认无密码用户
Remove anonymous users? (Press y|Y for Yes, any other key for No) : y
Success.


Normally, root should only be allowed to connect from
'localhost'. This ensures that someone cannot guess at
the root password from the network.
// 提示禁止远程root登陆
Disallow root login remotely? (Press y|Y for Yes, any other key for No) : no

 ... skipping.
By default, MySQL comes with a database named 'test' that
anyone can access. This is also intended only for testing,
and should be removed before moving into a production
environment.

// 提示删除默认自带的test数据库
Remove test database and access to it? (Press y|Y for Yes, any other key for No) : y
 - Dropping test database...
Success.

 - Removing privileges on test database...
Success.

Reloading the privilege tables will ensure that all changes
made so far will take effect immediately.
// 提示是否从新加载privilege tables
Reload privilege tables now? (Press y|Y for Yes, any other key for No) : y
Success.

All done!

 

若是只是修改成一个简单的密码，会报如下错误：

mysql>  ALTER USER USER() IDENTIFIED BY '12345678';
ERROR 1819 (HY000): Your password does not satisfy the current policy requirements

这个其实与validate_password_policy的值有关。

validate_password_policy有如下取值：

Policy	Tests Performed
0 or LOW	Length
1 or MEDIUM	Length; numeric, lowercase/uppercase, and special characters
2 or STRONG	Length; numeric, lowercase/uppercase, and special characters; dictionary file

默认是1，即MEDIUM，因此刚开始设置的密码必须符合长度，且必须含有数字，小写或大写字母，特殊字符。

有时候，只是为了本身测试，不想密码设置得那么复杂，譬如说，我只想设置root的密码为123456。

必须修改两个全局参数：

首先，修改validate_password_policy参数的值

mysql> set global validate_password_policy=0

而后

mysql> select @@validate_password_length;
+----------------------------+
| @@validate_password_length |
+----------------------------+
|                          8 |
+----------------------------+
1 row in set (0.00 sec)

validate_password_length参数默认为8，它有最小值的限制最小值为4，若是你显性指定validate_password_length的值小于4，尽管不会报错，但validate_password_length的值将设为4

mysql> set global validate_password_length=1;

mysql> select @@validate_password_length;
+----------------------------+
| @@validate_password_length |
+----------------------------+
|                          4 |
+----------------------------+
1 row in set (0.00 sec)