Creating dynamic dropdown lists - php

Question

I want to create dynamic select lists. For example: I have 5 students in my db. My goal is to create 5 selects ,and in every select all students which are in database. So if user inserts a 6th student in the database, the page should display 6 selects, and in every select names of 6 students.
I've tried with this code, but it only creates 1 select, containing 4 students(the first one from the db is missing).
The Code:
$con=mysqli_connect("localhost","root","","novi-studomat");
$exe="SELECT * FROM kolegij WHERE id_student='$id_student'";
$i=1;
$execute=mysqli_query($con,$exe);
while($result=mysqli_fetch_array($execute))
{
echo '<select name=student'.$i.'>';
echo '<option value="-1" >Choose student</option> <br/>';
while($res=mysqli_fetch_array($execute))
{
echo '<option value='.$res["id_student"].'>'.$res["name"].'</option> <br/>';
}
echo '</select>';
$i++;
}

Answer 1

$con=mysqli_connect("localhost","root","","novi-studomat");
$exe="SELECT * FROM kolegij WHERE id_student='$id_student'";
$i=1;
$execute=mysqli_query($con,$exe);
$select = '';
for($j = 0; $j < mysqli_num_rows($execute); $j++) {
$select .= '<select name=student' . $j . '>';
$select .= '<option value="-1" >Choose student</option> <br/>';
while($result=mysqli_fetch_array($execute)) {
$select .= '<option value=' . $res["id_student"].'>' . $res["name"] . '</option>';
$i++;
}
$select .= '</select>';
}
echo $select;
UPDATE
inside the while
$select = '<select name=student' . $j . '>';
$select .= '<option value=' . $res["id_student"].'>' . $res["name"] .
change this lines by this other
$select = '<select name="student' . $j . '">';
$select .= '<option value="' . $res["id_student"]."'>' . $res["name"] .
we missed the double quotes for value and in select name

Answer 2

Problem solved, I just needed to insert vars $exe and $execute inside for loop, so after every iteration $result is refreshed,otherwise it just prints options in first select...
CODE:
$con=mysqli_connect("localhost","root","","novi-studomat");
$exe="SELECT * FROM kolegij WHERE id_student='$id_student'";
$execute=mysqli_query($con,$exe);
$select = '';
for($j = 0; $j < mysqli_num_rows($execute); $j++)
{
$exe="SELECT * FROM kolegij WHERE id_student='$id_student'";
$execute=mysqli_query($con,$exe);
$select .= '<select name=student' . $j . '>';
$select .= '<option value="-1" >Choose student</option> <br/>';
while($result=mysqli_fetch_array($execute))
{
$select .= '<option value=' . $res["id_student"].'>' . $res["name"] . '</option>';
}
$select .= '</select>';
}
echo $select;