•cont. Report 13.3
–Re-Query Approach
•First, construct the body rows:
query Product, Brand and Average Customer Sales.
•Next, we query Brand and Average
Customer Sales.
•Lastly, we query and compute the
Average Customer Sales for all products.
•3 SQL queries.
–Each query is
successively simpler
–If we use a well-designed set of aggregate tables, each succesive summary level will enjoy a performance boost over the
previous.