如何在执行后立即打印被切除的sql

$wpdb对象具有为此设置的一些属性:

 global $wpdb;

// Print last SQL query string
echo $wpdb->last_query;

// Print last SQL query result
echo $wpdb->last_result;

// Print last SQL query Error
echo $wpdb->last_error;
 

注意:首先,您必须在WordPress根文件夹的define( 'SAVEQUERIES', true );文件中设置wp-config.php./p>

The $wpdb object has some properties getting set for that:

global $wpdb;

// Print last SQL query string
echo $wpdb->last_query;

// Print last SQL query result
echo $wpdb->last_result;

// Print last SQL query Error
echo $wpdb->last_error;

Note: First of all you have to set define( 'SAVEQUERIES', true ); in your wp-config.php file at root folder of WordPress.

我在这里列出了3种方法:

1. 使用SAVEQUERIES并在页脚中打印所有查询
2. 使用$wpdb->last_query仅打印执行的最新查询,这对于调试功能很有用.
3. 使用类似查询监视器的插件.

您需要将其添加到wp-config.php

  define('SAVEQUERIES', true);
 

然后在主题的页脚中添加以下代码:

  <?php
  if (current_user_can('administrator')){
   global $wpdb;
   echo "<pre>Query List:";
   print_r($wpdb->queries);
   echo "</pre>";
 }//Lists all the queries executed on your page
?>
 

或者,如果您只想打印最后执行的查询,则可以在$wpdb查询函数调用下面使用它.

 global $wpdb;
echo $wpdb->last_query;//lists only single query
 

第三种方法是使用诸如Query Monitor之类的插件,该插件详细列出了在页面上执行的所有查询,以及与之相关的其他详细信息,例如返回的行数和执行时间,或者它是否很慢查询. http://wordpress.org/plugins/query-monitor/

仅在DEV环境中使用此插件是个好主意,不应在活动站点上使其保持激活状态.另外,查询监视器有时可能会导致您的页面出现问题,例如,如果错误过多,则模板/页面上的5XX错误.

I've listed down 3 approaches in here:

1. Using SAVEQUERIES and printing all the queries in footer
2. Using $wpdb->last_query to print just the latest query executed, this is useful for debugging functions.
3. Using a plugin like Query Monitor.

You'd need to add this in your wp-config.php

 define('SAVEQUERIES', true);

Then in the footer of your theme add this code:

 <?php
  if (current_user_can('administrator')){
   global $wpdb;
   echo "<pre>Query List:";
   print_r($wpdb->queries);
   echo "</pre>";
 }//Lists all the queries executed on your page
?>

Or if you'd like to print just the last executed query, you can use this just below your $wpdb query function call.

global $wpdb;
echo $wpdb->last_query;//lists only single query

A 3rd approach would be to use a plugin like Query Monitor which lists all the queries executed on a page in detail, and other details associated with it like how many rows it returns and the time taken for execution or if it's a slow query. http://wordpress.org/plugins/query-monitor/

It's a good idea to use this plugin in DEV environment only and shouldn't be left activated on a live site. Also, Query Monitor can sometimes cause issues with your page, Like 5XX error on your template/page if there are too many errors.

您必须同时添加这两个函数,否则它将永远不会显示错误

 $wpdb->show_errors(); 
$wpdb->print_error();
 

此功能将向您显示这样的正确错误

You have to add both functions,otherwise it will never show error

$wpdb->show_errors(); 
$wpdb->print_error();

This function will show you proper error like this this

我想补充一点,@ kaiser投票最好的答案并不完全正确:

 // Print last SQL query string
$wpdb->last_query
 

返回的是 ARRAY ,而不是字符串.因此,要输出最后一个查询,您应该这样做:

 echo 'Last query: '.var_export($wpdb->last_query, TRUE);
 

I wanted to add that the best up-voted answer by @kaiser is not fully correct:

// Print last SQL query string
$wpdb->last_query

The return of it is ARRAY, not a string. So to output last query you should do this:

echo 'Last query: '.var_export($wpdb->last_query, TRUE);