Week 5 L1

Question 1

What is the repeating group problem ?

Answer 1

Relational model requires that each entry contains no more than a single data item. Multiple values in a cell is known as a repeating group.

Question 2

What is unnormalized form ?

Answer 2

A table with repeating groups

Question 3

What is first normal form?

Answer 3

repeated groups are eliminated vertically

no repeated groups are 1st normal form

Question 4

What is table decomposition

Answer 4

separating data into tables to remove redundancy. this is achieved through the use of FK and PK

Question 5

What is 1nf data redundancy ?

Answer 5

When there is redundant data in the first normalised form

Question 6

What are 1NF redundancy anomalies?

Answer 6

Can occur due to associations with tables. for example inserting an actor who had not stared in film yet. if deleting a film do we delete all actors in the film ?

Question 7

What is 2NF?

Answer 7

Decomposing tables again to avoid data redundancy. Avoids repeating groups and some dependencies

Question 8

What us 3NF

Answer 8

splitting tables once again to avoid things such as transitive dependencies