This is a function easily convertible into a method to use inside of a class that as the name says, get columns names from mysql table, will return all the columns names from a given table in the provided database. The mysql connection used is the native PHP driver PDO.

getColumnsNamesFromMysqlTable.php

<?php

/**
 *
 * @author  Paulo Silva(Exadra37)     exadra37 in gmail point com
 * @package exadra37/PDO
 * @version 0.0.1
 * @since   24/01/2014
 *
 */

// Report all PHP Errors
error_reporting(E_ALL);

// Set execution time to unlimited
set_time_limit(0);

// Use UK Time
date_default_timezone_set('Europe/London');

// THIS IS THE CONTENT OF SETTINGS.INC.PHP:
// define('_DB_NAME_', 'your_database_name');
// define('_DB_TABLE_NAME_', 'your_table_name');
// define('_DB_USER_NAME_', 'your_user_name');
// define('_DB_PASSWORD_', 'your_password');
// define('_DB_HOST_', 'localhost');
require_once 'config/settings.inc.php';

$host = _DB_HOST_;

$database_name = _DB_NAME_;

$table_name = _DB_TABLE_NAME_;

function getColumnsNamesFromMysqlTable($host, $database_name, $table_name)
{
    try {

        // Creating a connection to mysl database
        // If you already have a PDO connection instantiated uncomment the line 43 and do the following:
        //      - rename the function to getColumnsNamesFromMysqlTable($PDO)
        //      - Then call the function like this: getColumnsNamesFromMysqlTable($your_pdo_connection)
        $PDO = new PDO("mysql:host={$host};dbname={$database_name}", _DB_USER_NAME_, _DB_PASSWORD_);

        // Building the query
        $query = "
            SELECT `COLUMN_NAME`
            FROM `INFORMATION_SCHEMA`.`COLUMNS`
            WHERE `TABLE_SCHEMA`='{$database_name}'
            AND `TABLE_NAME`='{$table_name}'";

        // Executing the query, using the previous created connection
        $rows =$PDO->query($query);

        // One way to fetch the results
        // var_dump($result) will return:
        // array (size=4)
        //    0 => string 'recid' (length=5)
        //    1 => string 'rcode' (length=5)
        //    2 => string 'storeName' (length=9)
        //    3 => string 'scode' (length=5)
        foreach ($rows as $key => $row) {
            $result[] = $row['COLUMN_NAME'];
        }

        // The other way to do it
        // var_dump($result) will return:
        // array (size=4)
        //    0 =>
        //      array (size=1)
        //        'COLUMN_NAME' => string 'recid' (length=5)
        //    1 =>
        //      array (size=1)
        //        'COLUMN_NAME' => string 'rcode' (length=5)
        //    2 =>
        //      array (size=1)
        //        'COLUMN_NAME' => string 'storeName' (length=9)
        //    3 =>
        //      array (size=1)
        //        'COLUMN_NAME' => string 'scode' (length=5)
        //$result = $rows->fetchAll(PDO::FETCH_ASSOC);

    } catch (PDOException $e) {
        echo 'ERROR: '.$e->getMessage();
    }

    return $result;
}

// How to call the function
$result = getColumnsNamesFromMysqlTable($host, $database_name, $table_name);

// Uncomment following  3 lines to debug results
// echo '<hr>result<pre>';
// var_dump($result);
// echo '</pre><hr>';