Isolation Level

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You can set the isolation level in SQL Server using a resource setting. The *isolationLevel resource setting defines the four levels of isolation for transactions. This resource setting can have one of the following values (not case-sensitive):


Prevents other transactions from changing data that has already been modified.


Prevents dirty read: If a record is modified in a transaction, and a second transaction needs to read that record, this second transaction waits until the first transaction completes. This is the default value.


Prevents non-repeatable reads. Non-repeatable reads occur when one transaction reads a record, and a second transaction modifies that record. If the second transaction commits its changes, the first transaction subsequently reads results that are different from the original read.

· SERIALIZABLE (level 3)

Prevents phantom records. Phantom records occur when one transaction reads a set of records satisfying a search condition, and the data is changed in a second transaction. If the first transaction reads within the same query conditions, it obtains a different set of records.