使用 Dim 表在 Fact 表上创建数据仓库

Question

I'm trying to understand the logic on how dim tables are connected with Fact tables.

I currently have a fact table that has no data and have two Dim Tables that have data.

Dim Table 1: Suburbs

Dim Table 2: Restaurants

As Dim table have different number of rows. How do I make the Fact table link the Dim table with the suburbs and Restaurants that shows the correct order/results?

Answer 1

• Fact table is holding facts or numerals.
• Dimension table is holding dimensions or aspects about the facts.

The data stored in fact, determines the granularity of the facts. The granularity of facts decide the granularity of dimension tables.

Eg, Suburbs is a dimension: Holds the suburb details
Restaurants is a dimension: Holds the Restaurant details
FactRestaurantSales is a Fact: Holds the sales at Restaurant granularity level.

1 Pizza of $20 dollars were sold in a restaurant Pizza Garden in suburb Bellevue, will be stored as below:

DimSuburb:

+-------------+------------+
| DimsuburbId | Suburbname |
+-------------+------------+
|          1  | Bellevue   |
+-------------+------------+

DimRestaurant:

+-----------------+----------------+
| DimRestaurantId | RestaurantName |
+-----------------+----------------+
|              1  | Pizza Garden   |
+-----------------+----------------+

DimItem;

+-----------+----------+
| DimItemId | ItemName |
+-----------+----------+
|        1  | Pizza    |
+-----------+----------+

FactRestaurantSales:

+-----------------------+--------------+-----------------+---------+-------------+----------------+
| FactRestaurantSalesId |  DimSuburbId | DimRestaurantId | DimItem | DollarSales | QuantitySales  |
+-----------------------+--------------+-----------------+---------+-------------+----------------+
|                   1   |          1   |              1  |      1  |          20 |            1   |
+-----------------------+--------------+-----------------+---------+-------------+----------------+