Preventing repeat information being sent to the database.

AliceH

Hi guys 🙂
What is the best way to prevent repeated information being sent to the database? For example I created a chatterbox, and when someone posts a message in the chatterbox then clicks REFRESH the message gets sent again!

Is there an overall solution I could add to my application instead of just the chatterbox? For example create a DB Abstraction Layer and have it check if the information is a reapeat (although that sounds like it would make the site load much slower).

Thanks for reading!

LordShryku

Could add a select statement before that to see if it exists....

Or you could put a unique constraint on the DB column so it will just reject the SQL query

AliceH

Thanks for your reply 🙂

How does this forum work? When you post a thread or reply it directs towards a page that says "thanks for your message", does the sql take occurrence on that page? And then it redirects towards your new thread/reply so that hitting refresh doesn't resubmit the data?

LordShryku

Dunno. You'll hafta ask one of the vBulletin hackers. jstarkey would prolly know.

maxpup979

What about using next.val? thats how I've done it in the past...works like a champ...but Im also on Postgres...so I don't know if that works in mySQL

AliceH

What's next.val 😕

maxpup979

nextval is a sequence manipulation function--very similar to currval (returns the current highest value), except it returns the NEXT value that would be used...and it also increments the sequence.....ie...

lets say I have a table with a PK sequence of 1,2,3,4,5...I do a select nextval(fieldname) and it will return 6--and increment the sequence.so it I run the script again, I will get 7 etc....

make sense?

so I have page 1, gets my nextval--adds it to the form as a hidden field. if the user hits submit--form processes, clears out etc...no chance for dupes, unless they hit back, or refresh...but since the nextval is already calculated, and taken...it will not allow the dupe to be entered....just be sure you catch the error...

AliceH

makes perfect sense, thanks maxpup979 🙂

johnnyv

You should do this on the client side

use a javascript function that gets called on the onsubmit() event.

<script LANGUAGE="JavaScript"> </SCRIPT>

Then on your <form> tag

<form name="the_form" method="post" action="somepage.php" onSubmit="return submitOnce(this)">

if the user clicks the submit button more than once a popup appears and say that they have already submitted.