显示特定自定义帖子类型的所有帖子及其帖子元

Question

Can some one help me to display all the Posts and Postmeta of Specific custom post type

I have created a Custom Post Type 'Course' in a wordpress project, with some Custom Meta Boxes

I need to display all The Posts and Custom Meta Box Values of that Custom Post Type

I have tried the query below .

$query = "
SELECT   $wpdb->posts.ID,$wpdb->posts.post_title,$wpdb->postmeta.meta_key
FROM $wpdb->posts
LEFT JOIN $wpdb->postmeta ON ( $wpdb->posts.ID = $wpdb->postmeta.post_id)
WHERE               
$wpdb->postmeta.meta_key IN ('_course_code','_instructor_name')
AND    
$wpdb->posts.post_type = 'course'   
";

$results = $wpdb->get_results($query);       
echo "<pre>"; 
print_r($results);

By Grouping this query results it only gives only one meta_key value

And it's giving me the result :

Please notice the id, and post_title being displayed twice with new index

Array
(
    [0] => stdClass Object
        (
            [ID] => 10
            [post_title] => introduction to wordpress
            [meta_key] => _course_code
        )

    [1] => stdClass Object
        (
            [ID] => 10
            [post_title] => introduction to wordpress
            [meta_key] => _instructor_name
        )

    [2] => stdClass Object
        (
            [ID] => 13
            [post_title] => introduction to hacking
            [meta_key] => _course_code
        )

    [3] => stdClass Object
        (
            [ID] => 13
            [post_title] => introduction to hacking
            [meta_key] => _instructor_name
        )

)

But i am expecting the results as

Array
(
    [0] => stdClass Object
        (
            [ID] => 10
            [post_title] => introduction to wordpress
            [meta_key] => _course_code
            [meta_key] => _instructor_name
        )

    [2] => stdClass Object
        (
            [ID] => 13
            [post_title] => introduction to hacking
            [meta_key] => _course_code
            [meta_key] => _instructor_name
        )

)

Answer 1

I have manged to get the results by myself, putting my answer here hoping it will help others.

$query = "
            SELECT $wpdb->posts.ID,$wpdb->posts.post_title,
            PM1.meta_value as _course_code,
            PM2.meta_value as _instructor_name
            FROM $wpdb->posts
            LEFT JOIN $wpdb->postmeta AS PM1 ON ( $wpdb->posts.ID = PM1.post_id AND PM1.meta_key = '_course_code')
            LEFT JOIN $wpdb->postmeta AS PM2 ON ( $wpdb->posts.ID = PM2.post_id AND PM2.meta_key = '_instructor_name')
            WHERE $wpdb->posts.post_type = 'course'
            AND $wpdb->posts.post_status = 'publish'
            AND ((PM1.meta_key = '_course_code') AND (PM2.meta_key='_instructor_name')) 
            GROUP BY $wpdb->posts.ID
            ORDER BY $wpdb->posts.post_date DESC

         ";

$results = $wpdb->get_results($query);

echo "<pre>"; print_r($results); die("here");

Answer 2

First of all, don't do $wpdb->posts, because hard to read. Secondly, missing GROUP BY sql query part.

$posts = $wpdb->posts;
$postmeta = $wpdb->postmeta;
$query = "SELECT $posts.ID, $posts.post_title, $postmeta.meta_key
FROM $posts
LEFT JOIN $postmeta ON ( $posts.ID = $postmeta.post_id)
WHERE         
$postmeta.meta_key IN ('_course_code','_instructor_name')
AND  $posts.post_type = 'course'   
GROUP BY $posts.ID";

$results = $wpdb->get_results($query);       
echo "<pre>"; 
print_r($results);      
echo "</pre>";