function pdo_mssql($sql){

    $host = ***;
    $user = ***;
    $pass = ***;
    $db   = ***;

    try {
        $PDO = new PDO( 'dblib:host=' . $host . ';dbname=' . $db, $user, $pass );;
    }
    catch ( PDOException $e ) {
        echo 'MSSQL error: ' . $e->getMessage(); exit;
    }

    $result = $PDO->query( $sql );

    if (is_array($result)){
        $row = $result->fetchAll( PDO::FETCH_ASSOC );
    }else{
        $row = $result;
    }

    return $row;

}

$sql = "SELECT ....";
$return = pdo_mssql($sql);

foreach ($return as $row){

    $sql2 = "SELECT ...."
    $return = pdomssql($sql2);

    foreach ($return2 as $row2){
        // Do something
    }

    $sql2 = "SELECT ...."
    $return = pdomssql($sql2);

    foreach ($return2 as $row2){
        // Do something
    }

    $sql2 = "SELECT ...."
    $return = pdomssql($sql2);

    foreach ($return2 as $row2){
        // Do something
    }

    // Show results

}