SQL4

Question 0

Five normalization forms?

Answer 0

1NF: eliminate repeating group (duplications,multi valued attributes, same data type)
2NF: eliminate redundant data
3NF: eliminate columns not dependent on key (a fact about the key,the whole key, and nothing but the key)
4NF: isolate independent multiple relationships
5NF: isolate semantically related multiple relationships

Question 1

Normalization?

Answer 1

In a nutshell, is the elimination of redundant data to save space

Question 2

Three different types of constrains?

Answer 2

Primary key: an attribute or set of attributes that can be used to uniquely identify each row.
Foreign key
Composite ( unique) key

All the potential keys are known as candidate keys

Question 3

A composite primary key?

Answer 3

To define more than one column as your primary key

Many to many relationship

Question 4

Two types of indexes?

Answer 4

Clustered: is sorted and stored based on key values.(=row locator)
Non-clustered: the data rows are stored in an unordered structure. (Pointer-heap-row locator)

Only one clustered index is allowed for each table