![]() Note that the transaction is not committed. This may suggest an error in the UPDATE statement. Serializable is the default isolation level but MS DTC will respect the Isolation Level you specify in your TransactionOptions. In the script below, the Name value of every row is changed to "Ben". In the first window, start a new transaction and make an update to the sample table. This can be achieved by running SQL Server Management Studio (SSMS) and opening two query windows. We can demonstrate a dirty read by executing two transactions concurrently. See the index for the whole series Read committed is the second weakest of the four isolation levels defined by the SQL standard. However, if these do not cause a problem in your specific scenario, you can use the read uncommitted level to ensure that you achieve the best performance and the highest levels of concurrency. session 53 has isolation level 2 (READ COMMITTED), and the last SQL that was executed on this session was that 'SET TRANSACTION. ![]() In SQL Server and Azure SQL Database Managed Instance, the default database isolation level is read committed. It means that it is possible to encounter dirty reads, non-repeatable reads and phantom reads. There are four additional isolation levels (read uncommitted, repeatable read, serializable, snapshot) which can only be selected at the connection or statement level. When using this option, a transaction may read information that has been changed by other, uncommitted transactions. The least restrictive of the transaction isolation levels is read uncommitted. INSERT INTO People VALUES('Sam') Read Uncommitted
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