ia 3 important question and answer

Q1.  Explain concurrency control with an example

Q2.  explain schedule with an example

Q3.  shadow page

Q4 explain recovery techniques

Q5.  acid properties

Q6.  two phase locking with example

Q7 explain bcnf, 4nf, 5nf

Concurrency Control

• In the concurrency control, the multiple transactions can be executed simultaneously.
• It may affect the transaction result. It is highly important to maintain the order of execution of those transactions.

Problems of concurrency control

Several problems can occur when concurrent transactions are executed in an uncontrolled manner. Following are the three problems in concurrency control.

1. Lost updates
2. Dirty read
3. Unrepeatable read

1. Lost update problem