The effect of determinants on SQL
It is important to
understand the effect that determinants
have on the SQL that is generated. Determinants affect the grouping
and aggregation of data, including other query subjects that have
relationships with the query subject as well as the query subject
itself.
For example, consider the following information. Each Product Line contains many occurrences of Product Type. Each Product Type contains many occurrences of Product. For Product, Product Key is a surrogate key and Product Number is a business key that is used as an attribute. Data joined on Product Key is aggregated correctly when reported by Product Line or Product Type or both.
|
Determinant |
Key |
Group by |
Uniquely identified |
Attributes |
|---|---|---|---|---|
|
Product line |
Product line code |
Yes |
Product line |
|
|
Product type |
Product type code |
Yes |
Product type |
|
|
Product |
Product key |
Yes |
Cost Margin Product name Product number |