Php – Is database based chat room bad idea

In a lot of situations, the simple technique of "last writer wins" can be sufficient.

Last writer wins means that the last person to save has his changes kept; any changes made while that person was editing are lost.

While this might seem a crazy approach, consider that in many systems the source of change is to synchronise with the real world.

Consider a system listing customers with their addresses and phone numbers. Imagine that one of their customers, Mary, has recently moved house. She sent in a change of address card to your compand. Her husband, John, didn't know about this and has phoned in to update details through the customer centre. Coincidentally, the change of address card is being processed concurrently with the phone call.

Which change should be kept? It doesn't matter - because both edits will be changing the house address to the same value.

You also need to keep in mind the potential frequency of concurrent updates - it's actually pretty unlikely that the phone call and processing of the change of address card would happen at the same time. If the card was processed first, John would find the details already correct when he called; if the card was processed last, the operator would find the details already correct. In either case, no conflict.

Short Answer: You would definitely have less headaches with a single database.

Otherwise, you may end-up with record synchronization issues, as well as with record duplicates, in all local databases that you might use.

What would you need is just to create a DAL (data access layer) and make your client applications (desktop, wen, mobile, etc) access your database through your DAL.