MySQL randomly inserting records two or more times

briansmccabe

Hi. This is my first post, so I'd like to say thank you to the folks that provide this great resource. I am having a weird issue with PHP/MySQL. MySQL is adding a submitted record from a form multiple times. I know this is a relatively common problem that is seemingly virtually always due to errors in the code. However, this situation is slightly different. What is happening is the duplication is sometimes happening AFTER the initial submission, and AFTER additional records are successfully submitted.

So, for example, INSERT will add record with ID 123, then add 124, 125, 126, and then out of nowhere, record 127 will be identical to 123. Granted, it doesn't ALWAYS happen in this manner, but it often does.

Also, there's zero consistency to this dilemma. It doesn't happen with every record. It doesn't always limit itself to mere duplication. Sometimes, a record will end up in the database 3 or 4 times. I started including a unix timestamp of the moment of insert to try and track how far apart these inserts are occurring, and sometimes they're up to 25 minutes apart!

As everyone says....I've examined my code pretty thoroughly. It's as straightforward as can be. I'm the only person using the form, so I can ensure there's no hyperclicking going on. There's no javascript or other form of validation (I wrote it quick and dirty to get a bunch of data added swiftly, and this is what I get!). Just a GET to a script that runs the INSERT statement, then pushes the user back to the form with "header("location: ...")".

Any suggestions? I'm hoping someone is aware of something right off the bat that I'm not aware of regarding what I've described. I will post my code if needed.

Thanks

Brian

briansmccabe

Hi there -

You know, you make an excellent point - I honestly have no idea why I went with GET over POST. I've made many, many other forms over the years, with various levels/types of validation etc etc, and to my recollection, they've always used POST. I am going to switch everything to POST and see if that makes the difference. Also, I fully intended to revisit the lack of validation very soon...my plan was to get this entry form up and running, get the data in that had to get in pronto, then "finish out" the form in a proper manner before deploying it for every-day use. Nevertheless, there's no doubt a possibility that the presence of validation could have saved some of this headache. Fortunately, I needed to get 256 records into the database, and they're all there - nothing more, nothing less (at the moment, anyway). Thanks again for the help. I appreciate it. If I continue to see the hiccup after switching to POST, I'll post my code and we can go from there.

Thanks

Brian

Ashley_Sheridan

I've seen this a few times before with GET requests, because browsers make multiple requests in order to speed up the loading of the page for the visitor.

If you can switch to POST, that's great, but if not, then you'll have to do some trickery, like one of the following:

Add a timestamp and update only if no similar record exists within a certain time frame, say a couple hundred milliseconds
Add some for of multi-field primary key or unique index and use an ON DUPLICATE KEY UPDATE query, which should ensure just the one record