[聚合文章] Error!: SQLSTATE[HY000] [1045] Access denied for user ‘root’@’localhost’ (using password: YES)

Windows下安装了一套WampServer环境开发PHP程序，写了一段超级简单的程序进行数据库链接：

try {
    $dbh = new PDO("mysql:host=localhost;dbname=todolist", "root", 'root'); //初始化一个PDO对象
    echo "连接成功";
    $dbh = null;
} catch (PDOException $e) {
    die ("Error!: " . $e->getMessage());
}

在公司的环境下一点问题都没有，同样的方式进行配制的环境，在家里的电脑死活就不行，一执行就报错：

 Error!: SQLSTATE[HY000] [1045] Access denied for user ‘root’@’localhost’ (using password: YES) 

我确定用户名和密码都没有写错，但还是按照通常的解决方法试了一遍，还是不行：

In MySQL, a user is identified by both a username (test2) and a host (localhost).

The error message you are getting identify the user (test2) and host (localhost) values…

'test2'@'localhost'

Check to see if that user exists, using this query from a client you can connect from:

SELECT user, host FROM mysql.user

You’re looking for a row that has test2 for user, and localhost for host.

user     host       
 -------  -----------
 test2     127.0.0.1  
 test2     ::1        
 test2     localhost

If that row doesn’t exist, then the host may be set to wildcard value of %, to match any other host that isn’t a match.

If the row exists, then the password may not match. You can change the password (if you’re connected as a user with sufficient privileges, e.g. root

SET PASSWORD FOR 'test2'@'localhost' = PASSWORD('mysecretcleartextpassword')

Also verify that the user has privileges on objects in the database.

GRANT SELECT ON jobs.* TO 'test2'@'localhost'

引用： https://stackoverflow.com/questions/31154124/sqlstatehy000-1045-access-denied-for-user-usernamelocalhost-using-cakep/34445308

重新安装了一次WampServer，甚至还参考MySQL官方论坛寻找解决方案 https://forums.mysql.com/read.php?11,661415,661415 ，还是不行。

后面直接看起了MySQL的配制文件my.ini，看到端口号(port)的配制，想到可能是因为没有加端口号。然后把端口号加上试了一下。果然可以：

$dbh = new PDO("mysql:host=localhost:3307;dbname=todolist", "root", 'root'); //初始化一个PDO对象

就这么一个小失误，查问题查的跳楼的心都有了。现在大概明白原因了，WampServer是一个集成多个软件的一整套的开发环境，安装成功后会同时安装MySQL和MariaDB这两个数据库。MySQL默认的端口号是3306，而MariaDB默认的端口号是3307，可以查看他们的配制文件。而我使用的是MariaDB数据库，但PHP数据库链接时，没有加端口可能会使用默认的端口号3306，所以导致失败。

MySQL和MariaDB的区别和关系可参考： http://blog.csdn.net/liumiaocn/article/details/56665800