在下載MySQL解壓版並安裝完成後，出現了一些問題。

登入命令

第一次登入時，由於是解壓版，密碼為空。所以在輸入密碼時，直接回車就可以啦

mysql –uroot -p  

修改密碼

登入成功後，我想修改密碼，使用命令：

update user set password=password('root') where user='root'; 

結果總是提示Unknown column 'password' in 'field list'

原來新版本沒有password這個欄位了，改成authentication_string

把命令改成

update user
 
 set authentication_string=password('root') where user='root'; 

就可以啦

再一次重啟後出現如下問題

Your password has expired. To log in you must change it using a client that supports expired passwords

解決辦法：
進行mysql的bin開啟cmd

mysqladmin -uroot -p password

在Enter password：root，這裡root是我的密碼，也就是通過上面update更新密碼。
New password:輸入新密碼
confirm password：輸入確認密碼。

這裡講個小知識：在my.ini配置檔案中最後加上skip-grant-tables，可以是登入MySQL時，不進行許可權認證。（要是沒有my.ini，請拷貝my-default.ini，並改名字為my.ini）.
my.ini的配置資訊：

[mysqld]

# 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 = 128
 
M

# Remove leading # to turn on a very important data integrity option: logging
# changes to the binary log between backups.
# log_bin

# These are commonly set, remove the # and set as required.
 basedir = D:\Program Files\mysql-5.7.16-winx64
 datadir = D:\Program Files\mysql-5.7.16-winx64\data
 port = 3306
 max_connections=200
 bind-address = 0.0.0.0
# server_id = .....


# 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 

sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES 
#skip-grant-tables

這篇講解了MySQL ERROR 1045 (28000): Access denied for user ‘root’@’localhost’
(using password: NO)的真正原因。不過是在Linux環境中。