Refer to the sequence below. What is the isolation level of transaction E? session begins SET GLOBAL TRANSACTION ISOLATION LEVEL SERIALIZABLE; session ends session begins SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ; transaction A transaction B SET TRANSACTION ISOLATION LEVEL READ UNCOMMITTED; transaction C SET TRANSACTION ISOLATION LEVEL READ COMMITTED; transaction D transaction E session ends Serializable Repeatable read Read committed Read uncommitted

The following dependency graph shows the dependencies of four queries. Is a schedule from these queries conflict serializable? Yes 83 No 81 84 I don't have enough information to determine 82 Why is it important to have concurrency control in databases? Concurrency Control is needed so that multiple transactions can be executed at the same time. Concurrency Control is needed so that data can be updated correctly when multiple transactions are executed concurrently. Concurrency Control is needed to allow multiple users to edit the same record at the same time. O Concurrency Control is needed so that the database can schedule conflicts based on the priority of the transactions.