5.7之后

• password函數舊版16位，新版41位，可用select password(‘123456’)查看。
• md5加密算法，只有16位和32位兩種

authentication_string

且5.7之后移除了password，它采用了新的算法

• 5.7之前

mysql> select user,host,password from mysql.user;
ERROR 1054 (42S22): Unknown column 'password' in 'field list'

• 5.7之后

mysql> select user,host,authentication_string from mysql.user;
+------+-----------+-------------------------------------------+
| user | host      | authentication_string                     |
+------+-----------+-------------------------------------------+
| root | localhost | *8A7993B6A9F0539BBE570DB3FD66FC580093FB05 |
| root | %         | *8A7993B6A9F0539BBE570DB3FD66FC580093FB05 |
+------+-----------+-------------------------------------------+
2 rows in set (0.00 sec)

在5.7中

• PASSWORD() （已棄用5.7.6） 計算并返回密碼字符串

在8.0中

PASSWORD(str)
This function was removed in MySQL 8.0.11.

https://dev.mysql.com/doc/refman/8.0/en/encryption-functions.html#function_password