CHAPTER 9
Logical Data Models
What does business need?
Forget the technology
Enter logical
The highlighted row in Table 9.1 shows the focus of this chapter, which is the logical data model (LDM).
Table 9.1 The Logical Data Model is the focus of this chapter
|
|
Relational |
Dimensional |
|
Conceptual Data Model (CDM) |
‘One-pager’ on business rules |
‘One-pager’ on navigation |
|
Logical Data Model (LDM) |
Detailed business solution on business rules |
Detailed business solution on navigation |
|
Physical Data Model (PDM) |
Detailed technical solution on business rules |
Detailed technical solution on navigation |
A LDM takes the business need defined on a conceptual data model down to the next level of a business solution. That is, once you understand at a broad level the scope of an effort and what business people require to solve their problem, the next step is to come up with a solution for them in the form of a LDM. In this chapter, the logical data model is explained along with a comparison of relational and dimensional mindsets. We explain the relational techniques of normalization and abstraction, and dimensional terminology such as meters and dimensions. We will also practice building logical data models in ER/Studio.