Chapter 2: Introduction To Logical Data Modelling
Major Concepts of Logical Data Modelling (con.)
- Primary Key: identifying attribute or set of attributes which can be used to distinguish each occurrence. (”PK” in the left above a line in a logical data model diagram as shown in figure 2.2)
- Foreign key: an attribute or a set of attributes that completes a relationship by identifying the associated entity.
- Data dictionary: Manual or automated repository of information about applications, database, logical data models, users and access authorisations.
- One-to-one relationship: between two entities, represented by single-headed arrow
- One-to-many relationship: between two entities, represented by double-headed arrow.