connectdatabasephp formation

//dbphp
<?php
    $host = "localhost";
    $username = "root";
    $password = "";
    $obj=mysqli_connect($host,$username,$password,'class');
    /*if($obj)
        echo "Success<BR>";
    else
        echo"No Sucess<BR>";
*/
    $st='SELECT StudentID,SFirstname,SLastname FROM student';
    $result=mysqli_query($obj,$st);

    if(!$result)
    {
            echo mysqli_error().'<BR>';
            die('can not');
    }
    else
    {
        /*echo "complet";
        while($row=mysqli_fetch_assoc($result))
        {
            while(list($key,$value)=each($row))
                    echo $value.'<br>';
        }*/
    }
    echo'<table border="1">';
    echo '<tr>';
    echo '<td>';
    echo "StudentID";
    echo '</td>';

    echo '<td>';
        echo"Firstname";
        echo '</td>';
    echo '<td>';
        echo "Lastname";
    echo '</td>';
    echo '</tr>';
    echo '<br>';
    while($row=mysqli_fetch_assoc($result))
        {
            echo '<tr>';
            while(list($key,$value)=each($row))
                if($value=='')
                    echo $value.'<br>';
                else
                    echo '<td>'.$value.'</td>';
            echo '</tr>';

        }

    $result=mysqli_query($obj,'SELECT TeacherID,TFirstname,TLastname,RoomNo FROM teacher WHERE TeacherID="103" ');
    echo '</table>';
    echo'<table border="1">';
    echo '<tr>';
    echo '<td>';
    echo "TeacherID";
    echo '</td>';

    echo '<td>';
        echo"Fisrtname";
        echo '</td>';
    echo '<td>';
        echo "Lastname";
    echo '</td>';
    echo '<td>';
    echo "RoomNumber";
    echo '</td>';
    echo '<tr>';
    echo '<br>';
    while($row=mysqli_fetch_assoc($result))
        {
            echo '<tr>';
            while(list($key,$value)=each($row))
                if($value=='')
                    echo $value.'<br>';
                else
                    echo '<td>'.$value.'</td>';
            echo '</tr>';

        }

    echo'<table border="1">';
    echo '<tr>';
    echo '<td>';
    echo "Student";
    echo '</td>';

    echo '<td>';
        echo"Fristname";
        echo '</td>';
    echo '<td>';
        echo "Lastname";
    echo '</td>';
    echo '<td>';
        echo "Major";
    echo '</td>';
    echo '<td>';
        echo "TeacherID";
    echo '</td>';

    echo '</tr>';
    echo '<br>';
    $result=mysqli_query($obj,'SELECT StudentID,SFirstname,SLastname,Major,TeacherID FROM student WHERE StudentID="4011905"');
    while($row=mysqli_fetch_assoc($result))
        {
            echo '<tr>';
            while(list($key,$value)=each($row))
                if($value=='')
                    echo $value.'<br>';
                else
                    echo '<td>'.$value.'</td>';
            echo '</tr>';

        }
    mysqli_close($obj);



?>