编辑“Function Reference/wpdb Class”（章节）

== query - Run 数据库上的任何查询 ==

The <code>query</code> function allows you to execute ''any'' query on the WordPress database.  It is best to use a more specific function, however, for SELECT queries.

<code>query</code>函数能够使你在WordPress数据库中执行''任何的''查询。最好为SELECT查询使用更确切的查询：

%%% <?php $wpdb->query('query'); ?> %%%
; query : (string) The query you wish to run.

%%% <?php $wpdb->query('query'); ?> %%%
; query : (string) 你希望运行的查询。

If there are any query results, the function will return an integer corresponding to the number of rows affected and the query results will cached for use by other <code>wpdb</code> functions.  If there are no results, the function will return (int) 0.  If there is a MySQL error, the function will return FALSE.  ('''Note''': since both 0 and FALSE can be returned, make sure you use the correct comparison operator: equality <code>==</code> vs. identicality <code>===</code>).

如果有什么查询结果，函数会返回一个整数关于多少个组受到了影响而且查询结果会储存，让另一个<code>wpdb</code>函数使用。如果没有结果，函数会返回(int) 0。如果有个MySQL错误，返回会返回错误的。（'''注''':因为即可以返回0又可以返回错误的，确定你使用了正确的比较运算符：equality <code>==</code> vs. identicality <code>===</code>）。

Note: It is advisable to use the <code>wpdb->escape($user_entered_data_string)</code> method to protect the database against SQL injection attacks by malformed or malicious data, especially when using the INSERT or UPDATE SQL commands on user-entered data in the database.  See the section entitled "Escape for SQL Queries" below.

注：建议使用<code>wpdb->escape($user_entered_data_string)</code>方法来保护数据库，由不好的或者恶意的数据通过SQL袭击，特别是用户向数据库中输入数据使用插入或者更新SQL命令的时候。请看看下面标题为"躲避SQL 查询"这部分。

'''Additionally''', if you wish to access the database from your code file which is not placed inside one of the [http://codex.wordpress.org/Writing_a_Plugin#Names.2C_Files.2C_and_Locations standard plugin locations], you will need to <code>include_once()</code> the <code>wp-db.php</code> file ''as well as'' the <code>wp-config.php</code> file. Including only the <code>wp-db.php</code> file will not set the database connection information resulting in an error message  like "Wordpress could not connect to the database". 

'''此外'''，如果你想要从代码文件中访问数据库，但是你的代码文件不在[http://codex.wordpress.org/Writing_a_Plugin#Names.2C_Files.2C_and_Locations 标准的插件 locations]，你就需要<code>include_once()</code> <code>wp-db.php</code>文件''和''<code>wp-config.php</code>文件。只包含<code>wp-db.php</code>文件不会设置数据库连接信息，反而会产生错误信息像"Wordpress 不能够连接到数据库"。

It is always advisable to put your functionality inside a plugin. However, if you need it in some cases, this workaround is available.
For example, this is the code in a file has_great_code.php in the root/installation directory :

总是将函数放入插件中，是可取的。然而，有时候，如果你需要函数，可以使用这个workaround。例如，这是根/安装目录中的has_great_code.php的文件的代码。

<pre>
include_once('wp-config.php');
include_once('wp-includes/wp-db.php');
</pre>

<pre>
include_once('wp-config.php');
include_once('wp-includes/wp-db.php');
</pre>

=== Examples ===
=== 例子===
Add Post 13 to Category 2:

将第十三篇文章添加到类别2：

<pre>
$wpdb->query("
	INSERT INTO $wpdb->post2cat (post_id, category_id)
	VALUES (13, 2)");
</pre>

<pre>
$wpdb->query("
	INSERT INTO $wpdb->post2cat (post_id, category_id)
	VALUES (13, 2)");
</pre>



Delete the 'gargle' meta key and value from Post 13.

从第十三篇文章中删除'gargle' meta key和参数值。

<pre>
$wpdb->query("
	DELETE FROM $wpdb->postmeta WHERE post_id = '13'
	AND meta_key = 'gargle'");
</pre>


<pre>
$wpdb->query("
	DELETE FROM $wpdb->postmeta WHERE post_id = '13'
	AND meta_key = 'gargle'");
</pre>



''Performed in WordPress by <code>[[WordPress:Function Reference/delete post meta|delete_post_meta()]]</code>.''


''在WordPress中由<code>[[WordPress:Function Reference/delete post meta|delete_post_meta()]]</code>执行。''


Set the parent of [[WordPress:Pages|Page]] 15 to Page 7.

将[[WordPress:Pages|网页]]15的母网页设置为网页7。

<pre>
$wpdb->query("
	UPDATE $wpdb->posts SET post_parent = 7
	WHERE ID = 15 AND post_status = 'static'");
</pre>


<pre>
$wpdb->query("
	UPDATE $wpdb->posts SET post_parent = 7
	WHERE ID = 15 AND post_status = 'static'");
</pre>
说明	输入内容	输出结果
斜体	''斜体文字''	斜体文字
粗体	'''粗体文字'''	粗体文字
粗斜体	'''''粗斜体文字'''''	*粗斜体文字*