Controlling Transactions and Locks

Locks are the mechanism databases use to control problems that may arise from simultaneous multi-user access. Some common issues locks try to manage include; what happens when two users try to change the same piece of information at the same time - who wins? Or user one tries to read data while user two is making changes on the same information, - which version of the data should user one see, changed or unchanged? Without locks, these situations may cause the data or results of a query to be logically incorrect. Lock sophistication is a key difference between simple databases designed for single user applications and enterprise databases capable of simultaneously handling large volumes of multi-user actions. Article by Don Schlichting, more