What you are doing here is tottaly in secure and your data can be hacked / manipulate really fast.
Why dont you use a framework like codeignighter there are about 100 easy frameworks that will help you manage database a lot easyer.
Are you sure that you are updating the wrond ID? where id = 1
, seems to be not dynamic.
Please post your error http://www.w3schools.com/php/func_mysql_error.asp
I know it is not so related to your question, but you should see these light frameworks:
http://kohanaframework.org/
https://github.com/ElbertF/Swiftlet
http://ellislab.com/codeigniter