Problems can also occur with the locking mechanism within concurrency control, two examples of such problems are: Deadlock can be the first of two problems that can occur , the second problem that can occur is active locka. DeadlockWhen two resources try to be unlocked at the same time, however this cannot happen, so they need to wait with each other. If two or more processors are waiting for an object to be unlocked, they are waiting in a circulating chain. This means that when they are eventually available they will unlock and the process can be completed. Stalling is very common and can occur when processing many items, it is more likely to happen when processors are waiting to see a specific type of unique resources. A great example of this would be “Some computers, usually those intended for time-sharing and/or real-time markets, are often equipped with a hardware lock, or hard lock, which grants exclusive access to processes, forcing serialization ” Dead Lock, Introduction to Concurrency Control, 2006. A simple way to think about deadlock is to say that if two people's actions cannot be satisfied, essentially a deadlock has occurred. Live lock. This is very similar to deadlock, however changes are constantly occurring with the processors, yet there is no progression to the next stage of the process. An example of how a live lock situation occurs is the following: “when numerous people arrive at a four-way stop and you are not entirely sure who should proceed next. If no one makes the concrete decision to go, and all the cars continue to creep into the intersection out of fear that someone else might hit them, then some sort of livelock may occur "c. basic time stamping... middle of paper... is going to happen and it will also provide the user with a troubleshooting guide to facilitate and help him understand and assist the program during its main task. This troubleshooting feature has been included in newer versions of the Microsoft SQL Database package. Concurrency within an Oracle database If there is a single user database, the user can modify the data in the database without worrying about other users modifying or changing the same data at the same time, however the statements with which we have multiple concurrent transactions can be achieved at the same time . Within the Oracle database controlling data concurrency and consistency is vital because it can be a multi-user environment. Database researchers defined serializability as a process that gives transactions behavior that makes them appear as if they were all happening at the same time.