为了增强安全性，MySQL5.7为root用户随机生成了一个密码，在error log中，关于error log的位置，若是安装的是RPM包，则默认是/var/log/mysqld.log。mysql
通常可经过log_error设置sql
mysql> select @@log_error; +---------------------+ | @@log_error | +---------------------+ | /var/log/mysqld.log | +---------------------+ 1 row in set (0.00 sec)
可经过# grep "password" /var/log/mysqld.log 命令获取MySQL的临时密码安全
2016-01-19T05:16:36.218234Z 1 [Note] A temporary password is generated for root@localhost: waQ,qR%be2(5
用该密码登陆到服务端后，必须立刻修改密码，否则会报以下错误：测试
mysql> select user(); ERROR 1820 (HY000): You must reset your password using ALTER USER statement before executing this statement.
若是只是修改成一个简单的密码，会报如下错误：ui
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。this
validate_password_policy有如下取值：spa
| 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。插件
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。code
必须修改两个全局参数：orm
首先，修改validate_password_policy参数的值
mysql> set global validate_password_policy=0; Query OK, 0 rows affected (0.00 sec)
这样，判断密码的标准就基于密码的长度了。这个由validate_password_length参数来决定。
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：
validate_password_number_count + validate_password_special_char_count + (2 * validate_password_mixed_case_count)
其中，validate_password_number_count指定了密码中数据的长度，validate_password_special_char_count指定了密码中特殊字符的长度，validate_password_mixed_case_count指定了密码中大小字母的长度。
这些参数，默认值均为1，因此validate_password_length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。以下所示：
mysql> select @@validate_password_length; +----------------------------+ | @@validate_password_length | +----------------------------+ | 8 | +----------------------------+ 1 row in set (0.00 sec) mysql> set global validate_password_length=1; Query OK, 0 rows affected (0.00 sec) mysql> select @@validate_password_length; +----------------------------+ | @@validate_password_length | +----------------------------+ | 4 | +----------------------------+ 1 row in set (0.00 sec)
若是修改了validate_password_number_count，validate_password_special_char_count，validate_password_mixed_case_count中任何一个值，则validate_password_length将进行动态修改。
mysql> select @@validate_password_length; +----------------------------+ | @@validate_password_length | +----------------------------+ | 4 | +----------------------------+ 1 row in set (0.00 sec) mysql> select @@validate_password_mixed_case_count; +--------------------------------------+ | @@validate_password_mixed_case_count | +--------------------------------------+ | 1 | +--------------------------------------+ 1 row in set (0.00 sec) mysql> set global validate_password_mixed_case_count=2; Query OK, 0 rows affected (0.00 sec) mysql> select @@validate_password_mixed_case_count; +--------------------------------------+ | @@validate_password_mixed_case_count | +--------------------------------------+ | 2 | +--------------------------------------+ 1 row in set (0.00 sec) mysql> select @@validate_password_length; +----------------------------+ | @@validate_password_length | +----------------------------+ | 6 | +----------------------------+ 1 row in set (0.00 sec)
固然，前提是validate_password插件必须已经安装，MySQL5.7是默认安装的。
那么如何验证validate_password插件是否安装呢？可经过查看如下参数，若是没有安装，则输出将为空。
mysql> SHOW VARIABLES LIKE 'validate_password%'; +--------------------------------------+-------+ | Variable_name | Value | +--------------------------------------+-------+ | validate_password_dictionary_file | | | validate_password_length | 6 | | validate_password_mixed_case_count | 2 | | validate_password_number_count | 1 | | validate_password_policy | LOW | | validate_password_special_char_count | 1 | +--------------------------------------+-------+ 6 rows in set (0.00 sec)