使用wpdb连接到单独的数据库

是可能的.

wpdb对象可用于访问任何数据库和查询任何表.完全不需要与Wordpress相关,这非常有趣.

好处是可以使用所有wpdb类和函数,例如get_results等,因此无需重新发明轮子.

方法如下:

 $mydb = new wpdb('username','password','database','localhost');
$rows = $mydb->get_results("select Name from my_table");
echo "<ul>";
foreach ($rows as $obj) :
   echo "<li>".$obj->Name."</li>";
endforeach;
echo "</ul>";
 

Yes it's possible.

The wpdb object can be used to access any database and query any table. Absolutely no need to be Wordpress related, which is very interesting.

The benefit is the ability to use all the wpdb classes and functions like get_results, etc so that there's no need to re-invent the wheel.

Here's how:

$mydb = new wpdb('username','password','database','localhost');
$rows = $mydb->get_results("select Name from my_table");
echo "<ul>";
foreach ($rows as $obj) :
   echo "<li>".$obj->Name."</li>";
endforeach;
echo "</ul>";

在WordPress中,连接第二个数据库很容易,您只需创建WPDB类的新实例,并以与使用我们都知道并喜欢的标准$ wpdb实例相同的方式使用它.

假设第二个数据库具有与主WP相同的登录信息,您甚至可以使用wp-config.php中的预定义常量来避免对登录信息进行硬编码.

 /**
 * Instantiate the wpdb class to connect to your second database, $database_name
 */
$second_db = new wpdb(DB_USER, DB_PASSWORD, $database_name, DB_HOST);
/**
 * Use the new database object just like you would use $wpdb
 */
$results = $second_db->get_results($your_query);
 

Connecting to a second database is easy in WordPress, you simply create a new instance of the WPDB class and use it the same way you would use the standard $wpdb instance we all know and love.

Assuming the second database has the same login information as the main WP one you can even use the predefined constants from wp-config.php to avoid hardcoding the login information.

/**
 * Instantiate the wpdb class to connect to your second database, $database_name
 */
$second_db = new wpdb(DB_USER, DB_PASSWORD, $database_name, DB_HOST);
/**
 * Use the new database object just like you would use $wpdb
 */
$results = $second_db->get_results($your_query);

没有人这么说,所以我想我会添加一种更简单的方法.

只要您的附加数据库具有与wordpress数据库相同的用户/访问权限详细信息即可访问,您可以在表名之前使用数据库名

 $query = $wpdb->prepare('SELECT * FROM dbname.dbtable WHERE 1');
$result = $wpdb->get_results($query);
 

no one has said this so I thought I'd add an even easier way..

as long as your additional database has the same user/pass details to access it as your wordpress database you can use the database name before the table name like this

$query = $wpdb->prepare('SELECT * FROM dbname.dbtable WHERE 1');
$result = $wpdb->get_results($query);

虽然这些方法可以使用,但您将失去使用"其他"自定义功能(如get_post_custom和wordpress查询)的能力.简单的解决方法是

 $wpdb->select('database_name');
 

更改系统范围的数据库(一个mysql select_db).如果只想进行简单查询,则使用database.table方法,但是如果要访问另一个wordpress博客,则可以使用select.完成后,您只需要将其更改回去,否则您的博客可能会做一些奇怪的事情.

While these will work, you'll lose the ability to use the "other" custom features such as get_post_custom and wordpress queries. The simple solution is

$wpdb->select('database_name');

which changes the database system-wide (a mysql select_db). The database.table method works if you just want to make a simple query, but if you want to access another wordpress blog you can use select. You'll just need to change it back when you're done or your blog may do strange things.

我无法发表评论,但我想扩大Wadih M.的回答(很棒).

WP的数据库类是Justin Vincent的ezSQL的自定义版本.如果您喜欢该界面,并且想要创建一个非基于WordPress的网站,则可能需要查看一下:http://justinvincent.com/ezsql

I can't comment yet, but I wanted to expand on Wadih M.'s answer (which is great).

WP's database class is a customized version of Justin Vincent's ezSQL. If you like the interface and you're wanting to do a site that's not WordPress-based, you might want to check it out: http://justinvincent.com/ezsql

我正在努力使用$wpdb从需要更新两个博客的父站点连接到第二个博客数据库.我使用$wpdb->select($dbname, $dbh)选择第二个数据库,但是我仍然从第一个数据库中获得结果.

我通过在第二个数据库上调用WP函数之前调用wp_cache_flush()清除WordPress缓存来解决此问题.

I was struggling with using $wpdb to connect to a second blog database from a parent site that needs to update two blogs. I used $wpdb->select($dbname, $dbh) to select the second database, but I was still getting results from the first database.

I resolved the problem by calling wp_cache_flush() to clear the WordPress cache before calling WP functions on the second database.