One roll number cant be added again [duplicate] - php

Question

This question already exists:
Closed 10 years ago.
Possible Duplicate:
same roll number can not be added
I want my code to behave this way that if once i had added a roll number, it can not be added again in the registration..........same as if once an email adress is registered the error displays that EMAIL ADDRESS ALREADY BEEN TAKEN....
I am creating a function . of roll numbr value is 1 it shall display error and if not 1 it shall not display the error
function selectroll($studentname,$rollnumber)
{
$sql = "SELECT * FROM tblstuden WHERE studentname = 'studentname' and rollnumber = '$rollnumber';";
$obj_db = new DB();
$obj_db->query($sql);
$row = $obj_db->rsset();
if{
$val = 1;
}
else{
$val = 0;
}
$obj_db->db_close();
return $val;
}
$this->_id($row[id]);
$this->_studentname($row[studentname]);
$this->_rollnumber($row[rollnumber]);
$this->_classname($row[classname]);
$obj_db->db_close();
}
}
?>
and the function is called at the page by this method
<?php
if(isset($_POST['btnSubmit']) and $_GET['action'] == "Add")
{
$val = $Tblstuden->selectroll($_POST['studentname'],$_POST['rollnumber']);
if ($val =='1')
{
$Tblstuden->copyPostData();
$Tblstuden->insert();
echo"asdf";
}
redirect("index.php?page=studentlist");
}
else
{
echo"abc";
}
?>

Answer 1

You probably want
function selectroll($studentname,$rollnumber)
{
$sql = "SELECT * FROM tblstuden WHERE studentname = 'studentname' and rollnumber = '$rollnumber';";
$obj_db = new DB();
$obj_db->query($sql);
$row = $obj_db->rsset();
if ($row){
$val = 1;
$this->_id($row[id]);
$this->_studentname($row[studentname]);
$this->_rollnumber($row[rollnumber]);
$this->_classname($row[classname]);
}
else{
$val = 0;
}
$obj_db->db_close();
return $val;
}
}
?>
in line 8 of the top function - as otherwise the code won't compile.
Sub-note, your code is subject to mysql injection, you should look at using PDO (http://php.net/manual/en/book.pdo.php) for your database functions before you get used to the old method. Please. Do it now ;)