In ICE #9 “join4” we combine the join3 table and the custome…

In ICE #9 “join4” we combine the join3 table and the customer master table using the variable CustID and in inner join. This results in a table with 1,168 observations. If we instead link this tables using a left join and the TerritoryID variable, we get a table with 18,937 observations. In this joined table, there are observations where the customerID from the join3 table does not equal the customerID from the customer master table. 

In ICE #9 “join2” we left join our “join1” table and the cus…

In ICE #9 “join2” we left join our “join1” table and the customer invoices table using the InvoiceID variable. If instead we use a inner join, we find that 1 observation is excluded from the join1 table. This means that there must be a sales order from join1 where InvoiceID is null.