mysqli_multi_query not returnig any value
===

I fired the following query with the help of mysqli_multi_query. Which is executing properly but not returning any value. It returning blank. Whats wrong with the mysqli_multi_query or is there any alternative for this for firing multiple queries in codeigniter.

       $sql="LOCK TABLE xp_subunit WRITE; ";
        $sql .= "SELECT @myLeft := ".$_GET['lft'].", @myRight :=  ".$_GET['rgt'].", @myWidth :=  ".$_GET['lft']." - lft + 1
        FROM xp_subunit
        WHERE id =".$_GET['id']."; ";
    
        $sql .= "DELETE FROM xp_subunit WHERE lft BETWEEN @myLeft AND @myRight; ";
    
        $sql .= "UPDATE xp_subunit SET rgt = rgt - @myWidth WHERE rgt > @myRight; ";
        $sql .= "UPDATE xp_subunit SET lft = lft - @myWidth WHERE lft > @myRight; ";
        $sql.="UNLOCK TABLES;";
        
        //echo $sql;
        $query = $this->db->mysqli_multi_query($sql);

Thanks.