Hi,

Data records retrieved by a query are not prevented from modification by some other transactions. Non-repeatable reads may occur, meaning data retrieved in a SELECT statement may be modified by some other transaction when it commits.

The Read Committed isolation level allows a transaction to acquire a read lock (if it only reads the data) or a write lock (if it updates or deletes data) on the current row of data it is working with. This means the row of data being used by the transaction can not be changed or removed by other transactions until the lock is terminated.

thanks,