Transaction Terminologies in SQL Server 2008Let's review some terminology that is commonly used when talking about transactions:.
Beginning a transaction Specifying that all subsequent operations that occur after a transaction begins are assumed to lie within the transaction.
Rolling back a transaction Undoing operations that have occurred since a transaction began, thus restoring the affected data to its original state. This is done in the event of failure.
Committing a transaction Making permanent all operations that have occurred since a transaction began. A transaction is committed in the event of success.
Dirty read The operation of reading data that is yet to be committed. This occurs, for example, when transaction B is being blocked by transaction A, but because you have tweaked the isolation behavior, transaction B ends up reading transaction A's changes even though they have not been committed.
Nonrepeatable read A condition where transaction B modifies the data that transaction A was working with, during the lifetime of transaction A. As a result, transaction A reads modified data, and the original read cannot be repeated.
Phantom read Like a nonrepeatable read except that the number of rows changes between two reads within the same transaction. The rows that differ between the two reads are referred to as phantom rows.