Referential integrity

Question 1

What is referential integrity?(3 points)

Answer 1

1. Ensuring that changes are consistent across a database
   2.if a record is removed all references to it are removed
   3.A foreign key value must have a corresponding Primary key value in another table.

Question 2

Describe what is meant by the term ‘Durable’ in the context of ACID transactions.

Answer 2

data is not lost in case of power failure

Question 3

What does ACID stand for?

Answer 3

Atomicity, Consistency, Isolation and Durability.

Question 4

Give one disadvantage of using record locking.

Answer 4

Can cause deadlock

Question 5

Describe what is meant by the term ‘Atomic’ in the context of ACID transactions.

Answer 5

A transaction can only fully complete or not complete cant be partially completed.

Question 6

What is record locking and why is it used?

Answer 6

Record locking stops more than one user from changing the same data at the same time. It helps keep data safe and correct.

Question 7

Describe what is meant by the term ‘Isolation’ in the context of ACID transactions.

Answer 7

A transaction must not be interrupted by another transaction. Transaction must occur in isolation. Simultaneous executions of transactions should lead to the same result as if they were executed one after the other,

Question 8

Describe what is meant by the term ‘Consistency’ in the context of ACID transactions.

Answer 8

The database must move from one valid state to another after a transaction, must maintain referential inegrity after each transaction.

Question 9

What is Transaction processing?

Answer 9

Transaction processing means doing a group of steps together as one task.
All steps must finish, or none happen at all.