合并2个数组返回空php

Question

I am storing 2 arrays like this:

$gooff = array();

for($j=1;$j<=count($search_res);$j++)
{
   $post_id = $wpdb->get_results("SELECT DISTINCT post_id,meta_value from wp_postmeta Where meta_value"); 

$gooff = array_merge($post_id, $gooff);

}

But printing will result in empty result;

print_r($gooff); // Returning empty.

I think I am doing everything right. Then what causing this empty result? And yes there are values in my post_id array.

post_id result:

Array
(
    [0] => stdClass Object
        (
            [post_id] => 1129
            [meta_value] => java,php,html,css,mysql,jsp,cricket
        )

    [1] => stdClass Object
        (
            [post_id] => 1143
            [meta_value] => PHP,AJAX,MY,PROFILE,JAVA
        )

    [2] => stdClass Object
        (
            [post_id] => 1149
            [meta_value] => MY,PROFILE,PHP,DEVELOPER
        )

    [3] => stdClass Object
        (
            [post_id] => 1202
            [meta_value] => php,html&css
        )

    [4] => stdClass Object
        (
            [post_id] => 1209
            [meta_value] => php,html,wordpress,php,html,wordpress,php,html,wordpress,php,html,wordpress
        )

    [5] => stdClass Object
        (
            [post_id] => 1213
            [meta_value] => php,html,css,wordpress,jquery
        )

    [6] => stdClass Object
        (
            [post_id] => 1223
            [meta_value] => PHP,C++,C#,.Net,MYSQL
        )

)
Array
(
    [0] => stdClass Object
        (
            [post_id] => 1129
            [meta_value] => java,php,html,css,mysql,jsp,cricket
        )

    [1] => stdClass Object
        (
            [post_id] => 1143
            [meta_value] => PHP,AJAX,MY,PROFILE,JAVA
        )
)

Answer 1

Your sql query is returing object instead of array. Pass second parameter as ARRAY_A in get_results.

$post_id = $wpdb->get_results("SELECT DISTINCT post_id,meta_value from wp_postmeta Where meta_value",ARRAY_A);