PHP - Unique Records Only

I have a mysql table which will store users email addresses (each is unique and is the primary field) and a timestamp. 
I have added another column called `'unique_code' (varchar(64), utf8_unicode_ci)`.

What I would very much appreciate assistance with is;

a) Generating a 5 digit alphanumeric code, ie: 5ABH6 
b) Check all rows the 'unique_code' column to ensure it is unique, otherwise re-generate and check again 
c) Insert the uniquely generated 5 digit alphanumeric code into `'unique_code'` column, corresponding to the email address just entered. 
d) display the code on screen.

What code must I put and where?


**My current php is as follows:**

Code: [Select]
    require "includes/connect.php";
   
    $msg = '';
   
    if($_POST['email']){
   
    // Requested with AJAX:
    $ajax = ($_SERVER['HTTP_X_REQUESTED_WITH']  == 'XMLHttpRequest');
   
    try{
    if(!filter_input(INPUT_POST,'email',FILTER_VALIDATE_EMAIL)){
    throw new Exception('Invalid Email!');
    }
   
    $mysqli->query("INSERT INTO coming_soon_emails
    SET email='".$mysqli->real_escape_string($_POST['email'])."'");
   
    if($mysqli->affected_rows != 1){
    throw new Exception('You are already on the notification list.');
    }
   
    if($ajax){
    die('{"status":1}');
    }
   
    $msg = "Thank you!";
   
    }
    catch (Exception $e){
   
    if($ajax){
    die(json_encode(array('error'=>$e->getMessage())));
    }
   
    $msg = $e->getMessage();
    }
    }

I am having trouble showing reports for a given date range. Currently if I specify something like 11/03/2010 to 11/05/2010 I get results for all years within that month and day such as I may get results for 11/03/2008 11/03/2009 11/03/2010 11/04/2008 11/04/2009 11/04/2010 11/05/2008 11/05/2009 11/05/2010.
I am using the following code
$result = mysql_query("SELECT * FROM report WHERE date>='$date_begin' and date<='$date_end' ORDER BY 'date'",$db);

I use the following format in my date feild mm/dd/yyyy

My script is finally working as intended, but I want to add some additional data results.

I am trying to resolve how I can display a count of ONLY the records updated by my query:

// START :: Query to replace matches
mysql_query("UPDATE orig_codes_1a AS a
      JOIN old_and_new_codes_1a AS b ON concat(a.orig_code_1, a.orig_code_2) = concat(b.old_code_1, b.old_code_2)
   SET a.orig_code_1 = b.new_code_1,
                           a.orig_code_2 = b.new_code_2") or die(mysql_error());
// END :: Query to replace matches


In this query I count ALL records selection:


// START :: Create query to be displayed as final results of original codes table.
$result = mysql_query("SELECT * FROM orig_codes_1a") 
or die(mysql_error());  

I want to display a count on this part of the query:

....concat(a.orig_code_1, a.orig_code_2) = concat(b.old_code_1, b.old_code_2)....

Hello PHP freaks,   my codes dont allow me to log-in to Student Home with unique id. It says "Invalid Login or Password" this is my form

<tr bgcolor="#E1E1E1" class="stylesmall">
              <td width="35%" align="left" class="style7 style1">Learner Id : </td>
                <td width="65%" align="left"><input name="learner_id" type="text" id="learner_id" action="Student_Home.php" method="post"></td>
              </tr>
            <tr bgcolor="#E1E1E1" class="stylesmall">
              <td align="left" class="style7 style1">Password:</td>
                <td align="left"><input name="student_password" type="password" id="student_password"><
/td>

and this is my handler.

<?php
	session_start();
	include 'Connect.php';
	$flag = "";
	$learner_id = $_POST['learner_id'];
	$student_id = $_POST['student_id'];
	$student_password = $_POST['student_password'];
	$query = "select last_login_date from student_information where student_id='$student_id' and student_password='$student_password'";
	$result = mysql_query($query,$link_id);
	if(mysql_error() != null){
		die(mysql_error());
	}
	if($date = mysql_fetch_array($result))
	{
        $lastdate = $date['last_login_date'];
	$date2 = date("d-m-Y h:i A",strtotime($lastdate));
	$_SESSION["student_id"] = $_POST["student_id"];
        $_SESSION["lastlogin"] =$date2;
	$_SESSION["type"] = "Student";
	mysql_query("UPDATE student_information SET last_login_date=now() where student_id='$student_id'",$link_id);
	if(mysql_error() != null){
	die(mysql_error());
	}
	header("location:  Student_Home.php?id={$student_id}");
		 die();
	}
	else
	{
		$flag = "invalid";
		header("location:Student_login.php?flag=$flag");
		die();		
	} 	
?>

PLease help me PHP friends to correct my codes.