Not at all... In fact, what you are wanting to do is fundamental php/mySQL(ing)...
The reason it's not "read-Only" is because you have now searched both tables to retrieve the data, so as long as each table has a unique key value, then you will not have any problems manipulating the data.
Go to php.net and download the manual, and then go to mySQL.com and download that manual...
Use the mySQL manul to start gaining knowledge about how to retrieve data from databases, and display it. Then you can look through there to start learning how to INSERT, UPDATE and DELETE records...
Starting getting some code into place, and come on back and post it so we can help you tweak it. If you want a pre-written script, try hotscripts.com. They may not have the exact script you want, but there are enough examples out there, that you can adapt one to suit your nee