Submit more then 500 form records to mysql server using PHP only saved first 200 records. Other's not saved

There isn't sufficient information to determine a cause. We don't have enough of the code.

Did you check the data where the inserts stop? Does the code plain stop at the point where the data stops? Is there an error thrown? Is there error handling code around this sql operation that is swallowing the error instead of reporting it?

Since you're using what amounts to string concatenation to build the INSERT query, I'd be willing to bet the code crashes when the data has a ' character in it.