MSSQL Phantom Read

Data getting changed in current transaction by other transactions is called Phantom Reads. New rows can be added by other transactions, so you get different number of rows by firing same query in current transaction. In REPEATABLE READ isolation levels Shared locks are acquired. This prevents data modification when other transaction is reading the rows and also prevents data read when other transactions are modifying the rows. PHANTOM reads can be prevented by using SERIALIZABLE isolation level, the highest level.

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