What are Transactions?

The ACID properties of SQL Transactions, What are the different ACID properties of a transaction how they ensure that data is Atomic, Consistent, Isolated, and Durable.

What are Locks?

What is a Lock? What is the process that transactions use to lock records to provide transaction isolation.

Transaction Isolation Levels

Transaction Isolation Levels are used to control data access concurrency. Concurrency controls can be Pessimistic or Optimistic.