MySQL query not working with PHP - php

Question

I have a code in PHP where a field value entered should match with the values in a table in a database. If match found it must do some work, or else it must say "match was not found".
But whenever I check with values which are not in the table (database), it says "match has been found".
Here is the code:
<?php
include"conn.php";
if($_SERVER['REQUEST_METHOD'] == "POST"){
// Get data
// Vehicle Number
$vehicle_number = isset($_POST['VehicleNumber']) ?mysql_real_escape_string($_POST['VehicleNumber']) : "";
//ID card Nos.
$idcardno1= isset($_POST['idno1']) ? mysql_real_escape_string($_POST['idno1']) : "";
$idcardno2= isset($_POST['idno2']) ? mysql_real_escape_string($_POST['idno2']) : "";
//Text Messages
$Textmsg = isset($_POST['yourtext']) ? mysql_real_escape_string($_POST['yourtext']) : "";
if($idcardno1 == NULL )
{
//echo "Blank Fields";
$json = array("status" => "Failure", "msg" => "User has entered one or more than one null values so couldn't go for database operations");
}
else
{
$q=mysql_query("SELECT * FROM profile WHERE IDcardno1 ='$idcardno1' OR IDcardno2 = '$idcardno2' OR VehicleNumber ='$vehicle_number'" )or die(mysql_error());
if($q)
{
$num=mysql_num_rows($q);
if($num==0)
{
$json = array("status" => "Failure", "msg" => "Information not found");
print $num;
}
else{
$json = array("status" => "success", "msg" => "Information is stored and match has been found");
}
}
}
}
else{
$json = array("status" => "Failure", "msg" => "POST_Request method not accepted");
}
mysql_close($con);
/* Output header */
//header('Content-Type: application/json');
echo json_encode($json);
?>

Answer 1

Because you are using OR in your SQL query, it will return any database rows where there is an empty database value and empty form value. This may return rows where you were not expecting them (depending on your intention)
If that's the case, you may want to ONLY match on field values that are actually populated by changing the query to something like this:
$q = mysql_query("SELECT * FROM profile WHERE (IDcardno1 ='$idcardno1' AND '$idcardno1' <> '') OR (IDcardno2 = '$idcardno2' AND '$idcardno2' <> '') OR (VehicleNumber ='$vehicle_number' AND '$vehicle_number' <> '')" )or die(mysql_error());
(This is just one way to approach it)