Get Unique Post Meta Values From Meta Key

<?php
 /* Don't include the opening PHP tag*/
 * @param string $key Post Meta Key.
 * 
 * @param string $type Post Type. Default is post. You can pass custom post type here.
 * 
 * @param string $status Post Status like Publish, draft, future etc. default is publish
 * 
 * @return array
 */ 
 function get_unique_post_meta_values( $key = '', $type = 'post', $status = 'publish' ) {
    global $wpdb;
    if( empty( $key ) )
        return;
    $res = $wpdb->get_col( $wpdb->prepare( "
        SELECT DISTINCT pm.meta_value FROM {$wpdb->postmeta} pm
        LEFT JOIN {$wpdb->posts} p ON p.ID = pm.post_id
        WHERE pm.meta_key = '%s'
        AND p.post_status = '%s'
        AND p.post_type = '%s'
    ", $key, $status, $type ) );
    return $res;
}

This is how you:

Get Unique Post Meta Values From Meta Key

The Default is post. You can pass custom post type too.

You can check this example url BankDirectVip how I Get Unique Post Meta Values From Meta Key as a select element to filter the results.

Get Unique Post Meta Values From Meta Key

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