$a="SELECT COUNT(*) FROM `post` WHERE osoz=1 AND id_author=$id_au";
$a1 = mysqli_query($connect, $a);
$post1 = mysqli_fetch_assoc($a1);
echo $post1["COUNT(*)"];
Warning: mysqli_fetch_assoc() expects parameter 1 to be mysqli_result, boolean given in D:\OSPanel\domains\per.php on line 102
echo $post1["COUNT(*)"]