As NikiC pointed out you should not be using the mysql_ functions any longer, you can fetch the entire array in both PDO and mysqli, Here is a example to fetch all rows using the mysqli->fetch_all function, hope this helps!
//Database Connection
$sqlConn = new mysqli($hostname, $username, $password, $database);
//Build SQL String
$sqlString = "SELECT * FROM my_table";
//Execute the query and put data into a result
$result = $sqlConn->query($sqlString);
//Copy result into a associative array
$resultArray = $result->fetch_all(MYSQLI_ASSOC);
//Copy result into a numeric array
$resultArray = $result->fetch_all(MYSQLI_NUM);
//Copy result into both a associative and numeric array
$resultArray = $result->fetch_all(MYSQLI_BOTH);