hoe te controleren of de aangepaste tabel van WordPress leeg is of niet

Probeer dit :)

<?php
function schools_post_function()
{
    global $wpdb;
    $result = $wpdb->get_results("SELECT postid from wp_school_post WHERE `postid` IS NOT NULL");
    if(count($result) == 0)
    {
        echo "not filled";
    }
    else
    {
        echo "filled";

    }
}
?>