Create table columns on the fly on a mysql db

PHP - MySql - Dynamic Table Columns

<?php

$conn = mysqli_connect($ht, $ur, $pd);

mysqli_select_db($conn, $db);

//foreach req, check if the column exists, otherwise create it
foreach($_POST as $k => $v){

        $key = trim(mysqli_real_escape_string($conn, $k));

        $sql = "SELECT * FROM INFORMATION_SCHEMA.COLUMNS  WHERE TABLE_NAME='$tb' AND COLUMN_NAME='".$key."'";

        $result = mysqli_query($conn, $sql);

        if( mysqli_num_rows($result) == 0){
                $sql = "ALTER TABLE `$tb` ADD `".$key . "` text";
                mysqli_query($conn, $sql);
        }

        $insert[$key] = trim(mysqli_real_escape_string($conn, $v));
}

//insert the req
i($conn,$tb,$insert );


function i($conn, $table, $array) {
  $query = "INSERT INTO ".$table;
  $fis = array();
  $vas = array();
  foreach($array as $field=>$val) {
    $fis[] = "`$field`";
    $vas[] = "'".$val."'";
  }
  $query .= " (".implode(", ", $fis).") VALUES (".implode(", ", $vas).")";
  if (mysqli_query($conn, $query))
    return mysqli_insert_id($conn);
  else return false;
}
?>