Comparing two ways Co grant user authorizations, assign certain previliges to users vs. assign certain previliges to roles then assign a group of users to a role, which way is better in your option? Explain why. What is the concept of database transaction? Please use an example to explain it. Either all the operations in a work unit are completed successfully, or the work is aborted at the point of failure and undo all previous operations. Select the term that best fits this description: Isolation Consistency Atomicity Durability All of above