Chapter 3 - Tables and Keys

Question 1

Two Types of tables

Answer 1

1. Fact table

2. Dimension Table

Question 2

Fact table

Answer 2

• also called as Measure Group
• contains only foreign keys to the dimension tables (key columns) and all the
  non-key columns (measures) are numeric

Question 3

Dimension table

Answer 3

• do not contain foreign keys
• only a single column primary key
• a surrogate key.
• small in size
• change very slowly

Question 4

Factless fact table

Answer 4

Factless fact table is a fact table that contains NO measure columns

Question 5

3 kinds of Measures

Answer 5

1. Fully additive Measure (sales and costs)
2. Semi additive Measure (Stocks)
3. Non additive Measure (gross margin)

Question 6

Keywords to remember.. Surrogate keys and Degenerate Dimensions

Answer 6

1. A surrogate key is the primary key for a dimension table and is independent of any keys provided by source data systems.
2. Attributes such as SalesOrderNumber are called degenerate dimensions and
   these are kept as attributes of the fact table.