simple database call not working

Hello All, First post so be gentle 🙂

Im trying to do some simple database display code with php, and to begin im simply trying to select any data and display the array as a test but cant even do that.

so far I have tied plugins php snippets, insert php code snippet, php code widget.

i can echo etc as test but cant call any data.
(my table has no prefix it was imported to wordpress db manually.

initially trying :

$fetch = mysql_query("SELECT * FROM maindata") or die("selecting failed");
$array = mysql_fetch_array($fetch);
echo "<pre>";
print_r($array);
echo "</pre>";

then after googling for help tried:

global $wpdb;
$result = $wpdb->get_results( "SELECT * FROM maindata" );
$array = mysql_fetch_array($result);
echo "$array";

then exporting data to separate database and using a new connection:

global $wpdb;
$user="newuser";
$pass="newpass";
$db="newdb";

$link = mysql_connect("localhost", $user, $pass);
	if (! @link) {
			die ("coudnt connect");
		}
	mysql_select_db("$db")
		or die ("selecting failed");

$result = $wpdb->get_results( "SELECT * FROM maindata" );
$array = mysql_fetch_array($result);
echo "$array";

the strange thing is im not getting “selecting failed’ errors, just no data.
crazy is on the approach so im hoping someone can get me over this hurdle before i reach quiet boil.

thanks in advance.
steve
WordPress 4.2.2 running MH Magazine theme.