Joins
This book assumes basic knowledge of joins, specifically inner, left-outer, right-outer, and full-outer joins. If you are not familiar with the basics of joins, consider taking W3Schools' SQL tutorial at https://www.w3schools.com/sql/default.asp. The basics are not difficult, so it won't take you long to get up to speed.
The terms simple join and complex join mean different things in different contexts. For our purposes, we will consider a simple join to be a single join between two tables. Every other instance of joining will be considered complex.
The following screenshot shows a star schema, as an example of a complex join:
Figure 4.4: Star schema
A star schema consists of a fact table (represented by FactInternetSales in Figure 4.4) that references one or more dimension tables (DimCurrency, DimSalesTerritory, DimCustomer, DimProduct, and DimPromotion). The fact table typically contains measures, whereas the dimension tables, as the name suggests...
