foreach for discinct value和多个结果在同一行

In a nutshell:
I want to create a list for students and grades. When I get my sql, I get many grades for the same student. What I'm trying to do is this:

Student 1 -> Grade 1 -> Grade 1 -> Grade 3
Student 2 -> Grade 1 -> Grade 2 -> Grade 3

My sql pulls all the records in the database which is great but how can I get it to display like this?

SQL is very standard

$query_getGradesTr1 = "SELECT gradeID, studentID, grades.examID, grade FROM grades, exams WHERE exams.trackID=1 AND grades.examID=exams.examID";
$getGradesTr1 = mysql_query($query_getGradesTr1, $Site) or die(mysql_error());
$row_getGradesTr1 = mysql_fetch_assoc($getGradesTr1);
$totalRows_getGradesTr1 = mysql_num_rows($getGradesTr1);

I thought about using a foreach to go through the results, basically foreach studentID give me all the grades associated with them and repeat for each students...
But I get multiple results with same StudentID then another studentID, like this:

Student 1 -> Grade 1
Student 1 -> Grade 2
Student 1 -> Grade 3
Student 2 -> Grade 1
Student 2 -> Grade 2
Student 2 -> Grade 3

Any suggestions??

Do this:

$current_student = NULL;
foreach($totalRows_getGradesTr1 as $each) {
    // Check here is student does not matches to previous student
    if($each->studentID !== $current_student) {
        // If not matches then print, else ignore
        echo "$each->studentID";
    }
    // Assign to check again in next loop
    $current_student = $each->studentID;
    // Always print grade
    echo "-> $each->gradeID";
}

Another solution is, twice loop the array and make each studentId as array key assign all grades to the studentID, like:

$students_grades = array();
foreach($totalRows_getGradesTr1 as $each) {
    if(!isset($student_grades[$each->studentID]) {
        $student_grades[$each->studentID] = array();
    }
    $student_grades[$each->studentID][] = $each->gradeID;
}

// Then nested loop here and print records
foreach($student_grades as $studentID => $grades) {
    echo "$studentID -&gt; " . implode('-&gt;', $grades) . "<br>";
}