Stop data inserting into a database twice

Question

I was wondering what methods/preventions other programmers use to stop data being entered twice into a MySQL database when a user refreshes on the same page as a form? Obvio

Answer 1

I'd agree with Ilya there and add that you should use some client javascript to disable the 'submit' button once it's been clicked or present a modal dialog (css can help you here) to avoid multiple clicks on the submit button.

Lastly, if you don't want the data in your database twice then also check your database for the data before you try to insert it. If you do allow duplicate records but don't want rapid repeat insertions from a single source then I'd use a time/date stamp and IP address fields to allow for a time-based 'lockout' in my submission code, i.e. if the IP is the same and the last submission time was less than 5 minutes ago then don't insert the new record.

Hope that gives you some ideas.

Answer 2

Try including something in your forms to prevent double-submission, preferably at the same time protecting against cross-site request forgery. I recommend using what I call a formkey, which is a one-use field that uniquely identifies a form submission, tying it to an individual user at an individual address. The concept goes under other names too, but the short note I've linked to explains it well enough.

Answer 3

You can use a token to prevent the page from being processed again! Such a procedure is used in a lot web frameworks !

The pattern you should use is the "Synchronizer Token Pattern"! If you have a serviceoriented application, you can save your status in the Database.

The data can be send via JavaScript or by a hidden form field.

You should also have a look at libaries with out of the box support for things like this! Grails is such one!

See: http://www.grails.org/1.1-Beta3+Release+Notes ...

<g:form useToken="true">

...

withForm {
   // good request
}.invalidToken {
   // bad request
}

..

Answer 4

Process the form, then redirect to the results page. Reload then only redisplays the results page.