<?php
    $username = "";
    $password = "";
    $database ="";
    $con = new mysqli("localhost",$username,$password,$database) or die("Error " . mysqli_error($con));
    $con->query("SET NAMES 'utf8'");
    $column = 'column_name';
    $table = 'table_name';
    $type = 'INT(1)';
    $default = '0';
    $after = 'column_name';

    $default = (!EMPTY($default)) ? 'NOT NULL DEFAULT ' . $default : '';

    // query
    $query_table = "SELECT $column from `$table`";
     if ($result_table = $con->query($query_table)) {
         if ($result_table->num_rows > 0) {
            // $sql = "ALTER TABLE `$table` ADD `$column` $type $default AFTER `$after`";
            // $sql = "ALTER TABLE `product1` CHANGE `hit` `hit` INT(11) NOT NULL DEFAULT '0'";
            // if (!mysqli_query($con,$sql)) {
                // echo 'Error : '. $domain . '-' . mysqli_error($con) .'<br />';
            // } else {
            // echo table updated<br />';
            // }

            echo $table . ' column already exists';
         }
     } else {

            // echo 'Error: ' . $domain . '- column does not exist<br />';
            $sql = "ALTER TABLE `$table` ADD `$column` $type $default AFTER `$after`";
            if (!mysqli_query($con,$sql)) {
                echo 'Error : $table update.' - ' . mysqli_error($con) .'<br />';
            }
            echo $table . ' updated<br />';
     }