Check database for duplicate entries

peter-cooper
peter-cooper used Ask the Experts™
on
I am trying to find a way to check for duplicate entries in a mysql database. When I say duplicate, if the value already exists in a table, then deny the entry.

I am using jquery to connect to php and would appreciate some guidance as to how I can possibly code this. I have tried various if statements, but all error or fail miserably. I have posted the relevant part of the code as all other areas ie; validation are working ok. Also assume, all db calls and connections are in place. Thanks

submitHandler: function()   {
                if ($("#USRboxint").valid() === true)  { 
                var data = $("#USRboxint").serialize() + '&submit=true';
                $.post('/domain/users/boxesadd.php', data, function(msgs) {

               var messageOutputs = '';
                for (var i = 0; i<msgs.length; i++){

                    messageOutputs += msgs[i].box+'  ';
                    //console.log(messageOutputs);    
                }

                $("#USRboxint").get(0).reset();

                var $dialog = $('<div id="dialog"></div>').html('<br /><b>Your entry successfully submitted.<br /><br />Thank you.</b>');
                   $dialog.dialog({
                   autoOpen: true,
                   modal: true,
                   title: 'New Entry successfull',
                   width: 400,
                   height: 200,
                   draggable: false,
                   resizable: false,
                   buttons: {
                   Close: function() {
                   $( this ).dialog( "close" );
                   }
                   }
                   });


                }, 'json');

         } else

         { 
           return; 
         }
        },
        success:    function(msg)   {

        }

Open in new window


PHP Code

<?php

         $status = mysql_real_escape_string($_POST['status']);
         $company = mysql_real_escape_string($_POST['company']);
         $requested = mysql_real_escape_string($_POST['requested']);
         $activity = mysql_real_escape_string($_POST['activity']);
         $address = mysql_real_escape_string($_POST['address1']);
         $service = mysql_real_escape_string($_POST['service']);
         $box = mysql_real_escape_string($_POST['box_add']);
         $date = DateTime::createFromFormat('d/m/Y', $_POST['datepicker']);
         $destdate = $date->format('Y-m-d');
         $authorised = mysql_real_escape_string($_SESSION['kt_name_usr']);
         $submit = mysql_real_escape_string($_POST['submit']);
         $dept = mysql_real_escape_string($_POST['dept']);

         $array = split('[,]', $_POST['box_add']);

         if (isset($_POST['submit'])) {

          $form = array();
          foreach ($array as $box) {


          // **check for dupe here**

         $form[] = array('dept'=>$dept, 
                     'company'=>$company,
                     'address'=>$address,
                     'service'=>$service,
                     'box'=>$box,
                     'destroydate'=>$destroydate,
                     'authorised'=>$authorised,
                     'submit'=>$submit);

    $sql = "INSERT INTO `temp` (service, activity, department, company, address, user, destroydate, date, item, new) VALUES ('$service', '$activity', '$dept', '$company', '$address', '$requested', '$destdate', NOW(), '$box', 1)";
    $result = runSQL($sql) or die(mysql_error());
          }

       } 
       $result=json_encode($form);

         echo $result;
?>

php jquery 

Open in new window

Comment
Watch Question

Do more with

Expert Office
EXPERT OFFICE® is a registered trademark of EXPERTS EXCHANGE®
Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
Firstly, which part of your record identifies it as a duplicate? i.e which field needs to be unique in your database.

Normally the way you do this is to set a UNIQUE index on the particular field in your table. When you then try and insert the record in PHP, the database will automatically fire an error with a code of 1062. You then check for this error an act accordingly:

mysql_query(yourInsertStatement);
if (mysql_errno() == 1062) {
   //you have a duplicate
}

Author

Commented:
Hi Chris

The record in question is the field 'item'.  I am not familiar at all with this way of working.  How would I amend my db to accept this 'UNIQUE' entry? Thanks
Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
Peter,

Several ways to do it depending on how you manage your database, but basically you run this query:

ALTER TABLE temp ADD UNIQUE (item);

If you're using phpMyAdmin, select your 'temp' table, then the Structure tab. click on the Unique button for the 'item' column.
Become a Certified Penetration Testing Engineer

This CPTE Certified Penetration Testing Engineer course covers everything you need to know about becoming a Certified Penetration Testing Engineer. Career Path: Professional roles include Ethical Hackers, Security Consultants, System Administrators, and Chief Security Officers.

Author

Commented:
Only problem I foresee with that approach chris, is would I not need 2 entries for the sql query. 1 for the item and 1 for the rest or can I incorporate your suggestion as 1 query. Thanks
Most Valuable Expert 2018
Distinguished Expert 2018

Commented:
Not sure I follow.

You run the ALTER TABLE query once - now! And the unique constraint is permanently added to your table.

Then in your PHP script, you just run as normal, but whenever you try to insert a record that contains a duplicate 'item', error 1062 would be raised.

Author

Commented:
Ok at the moment I have this query:

$sql = "INSERT INTO `temp` (service, activity, department, company, address, user, destroydate, date, item, new) VALUES ('$service', '$activity', '$dept', '$company', '$address', '$requested', '$destdate', NOW(), '$box', 1)";

How do I adapt your code to include to also insert the other values. ie; does it become

$sql = "ALTER TABLE temp ADD UNIQUE (item) (service, activity, department, company, address, user, destroydate, date, item, new) VALUES ('$service', '$activity', '$dept', '$company', '$address', '$requested', '$destdate', NOW(), '$box', 1)";

Open in new window

which I know is incorrect. Thanks
Most Valuable Expert 2018
Distinguished Expert 2018
Commented:
No. On your database, using a tool such as phpMyAdmin, you run the ALTER TABLE query. You only do that once - do it now! Once that's done, your table will have a unique constraint on it permanently - job done! It has nothing to do with your PHP script.

After that's done, you adapt your PHP to catch the 1062 error:

$sql = "INSERT INTO `temp` (service, activity, department, company, address, user, destroydate, date, item, new) VALUES ('$service', '$activity', '$dept', '$company', '$address', '$requested', '$destdate', NOW(), '$box', 1)";
mysql_query($sql);
if (mysql_errno() == 1062) {
   //you have a duplicate
} else {
   //you don't have a duplicate
}

Open in new window

As an aside, at some point in the very near future you are going to have to change your code from using the mysql library to using the PDO or mysqli library - the mysql library is deprecated and will be removed from PHP altogether.
Most Valuable Expert 2011
Top Expert 2016

Commented:
An article showing how to make the required move away from the deprecated MySQL extension is available here:
http://www.experts-exchange.com/Web_Development/Web_Languages-Standards/PHP/PHP_Databases/A_11177-PHP-MySQL-Deprecated-as-of-PHP-5-5-0.html

A page mapping the familiar but deprecated MySQL_xxx() functions to the modern extensions is available here:
http://www.iconoun.com/mysql_mysqli_pdo_function_map.php

In my experience there are some things that can help you make this conversion smoothly. It is quite OK to make two simultaneous connections to the DB server, so you can keep the existing MySQL connection and add a MySQLi connection.  Once you have done that you can convert the PHP code one query at a time.  The PHP syntax is easiest if you use object-oriented MySQLi as shown in the article.

Author

Commented:
Thanks very much Chris. Helpful as usual.

Author

Commented:
Thanks Ray. Will check it out.

Do more with

Expert Office
Submit tech questions to Ask the Experts™ at any time to receive solutions, advice, and new ideas from leading industry professionals.

Start 7-Day Free Trial