Regarding An Admission Number Validation

[heshan]

I want something like this to be done as a validation.

 

In my form there 3 fields. Admission Number, Year and Term.

 

If an user enters an admission number which is not exist in my database table a proper validation should display as "Invalid admission number". How this can be done?

 

I have already validated marks added.

 

<?php
$con=mysql_connect("localhost","root","");
mysql_select_db("student_management",$con);
$admission_no=$_POST["admission_no"];
$term=$_POST["term"];
$year=$_POST["year"];
//validate

$query="SELECT COUNT(*) FROM mark INNER JOIN exam ON mark.exam_id=exam.exam_id
    WHERE mark.admission_no='$admission_no' AND exam.exam_name='$term' AND exam.year='$year'";
$result=mysql_query($query);
$row=mysql_fetch_array($result);
if($row[0]==0)
 {
header("location:addStudentMarkForm.php?admission_no=".$admission_no."&term=".$term."&year=".$year);
exit();

}else{

?>
<?php
echo "For this admission number ".$admission_no." tream".$term." marks has been already Added.";
echo "<BR><BR><BR>";
echo "<a href='addStudentMark.php'>Go to Add student mark page.</a>";
exit();
}

}
?>

[Jessica]

What are you stuck on? You've already done 1, what's the problem?

[heshan]

I have tried this one..But nothing happens.

 

<?php
if ($_POST){
   $admission_no=$_POST["admission_no"];
   if (!$admission_no){
   $msg = "An invalid number";
   }
}
?>

[Jessica]

Do you have error reporting on?

You'll want to use isset, and sanitize your data.

Use print_r to see what was POSTed

[heshan]

I have used this one..But it didn't work either..No output.

 

<?php
if (isset($_POST)){
   $admission_no=$_POST["admission_no"];
   if (!$admission_no){
   $msg = "Invalid id";
print_r($admission_no);

   }
?>

[Jessica]

 

If there's no admission number, why would printing it to the screen do any good?

Do you understand what your code does? Did you lookup what print_r does?

[heshan]

Actually not..i have very little understanding..Could you please help me??