wp_query with a group by clause

@nspace1999, You can use function something like below to fetch all custom post types title

<?php
$args = array(
    'post_type' => 'custom_post_type',
);
$loop = new WP_Query($args);

while($loop->have_posts()): $loop->the_post();
    the_title();
endwhile;
wp_reset_query();
?>

…and add a filter something like to append a GROUP BY clause to the current WP_Query

function custom_posts_groupby( $groupby, $query )
{
    global $wpdb;
    $groupby = "{$wpdb->posts}.ID";

    return $groupby;
}
add_filter( 'posts_groupby', 'custom_posts_groupby', 10, 2 );

I hope this helps.

Hello… than you for answering. Actually I need somethiing more complex.

I made a custom query and it worked for me :

SELECT   mt1.*, mt2.*, GROUP_CONCAT(DISTINCT CONCAT(mt2.meta_value, '' , mt3.meta_value))  FROM wpjght_posts  INNER JOIN wpjght_postmeta ON (wpjght_posts.ID = wpjght_postmeta.post_id)
INNER JOIN wpjght_postmeta AS mt1 ON (wpjght_posts.ID = mt1.post_id)
INNER JOIN wpjght_postmeta AS mt2 ON (wpjght_posts.ID = mt2.post_id)
INNER JOIN wpjght_postmeta AS mt3 ON (wpjght_posts.ID = mt3.post_id) WHERE 1=1  AND wpjght_posts.post_type = 'kine' AND (wpjght_posts.post_status = 'publish' OR wpjght_posts.post_status = 'future' OR wpjght_posts.post_status = 'draft' OR wpjght_posts.post_status = 'pending') AND (wpjght_postmeta.meta_key = 'wpcf-lat'
AND mt1.meta_key = 'wpcf-lng'
AND mt2.meta_key = 'wpcf-nom'
AND mt3.meta_key = 'wpcf-prenom' ) GROUP BY mt1.meta_value, wpjght_postmeta.meta_value ORDER BY wpjght_posts.post_date DESC

After 2 days working on it, hope it could help someone.