When creating the star schema models below, be sure to designate an appropriate primary key for each fact table and dimension table. a) b) Using the data shown above for the ZAGI Retail Company Scenario, create a dimensional model containing an aggregated fact table, where a fact table shows a summary of units sold and dollars sold for daily purchases of each product in each store. Next, create a new dimensional model containing a detailed fact table, where the fact table shows the units sold and dollars sold for each transaction for store, customer, product, and month. Include additional elds as needed, including time {11ime). Be sure to include an appropriate primary key for the fact table that identifies each row (i.e., transaction and each product in the transaction). Assume that ZAGI also needs to track product returns by customers stores, and months. Include an additional fact table that shows the units returned and the dollars returned for each return transaction. In other words, create a constellation (star schema with two fact tables). Be sure to include an appropriate primary key for the fact table that identies each row (i.e., return transaction and each product in the transaction)