Entity Integrity
Ensures that there are no duplicate records within the table and that the field that identifies each record within the table is unique and never null
Entity Integrity is the mechanism the system provides to maintain primary keys
Referential Integrity
Refers to the accuracy and consistency of data within a relationship
In relationships, data is linked between two or more tables
So referential integrity requires that, whenever a foreign key value is used it must reference a valid, existing primary key in the parent table.
Domain Integrity
The allowed values of an attribute create domain integrity, which ensures that all data in a field contains valid values
Domain integrity is defined by: data type, such as integer, character, or decimal.
Conceptual Data Model
A conceptual data model identifies the highest-level relationships between the different entities
Features of conceptual data model include:
the important entities and the relationships among them
No attribute is specified
Logical Data Model
A logical data model describes the data in as muchdetail as possible, without regard to how they will be physically implemented in the database.
Features of a logical data model includes
All entities and relationships among those entities
All attributes for each entity are specified
The primary key for each entity is specified
Foreign keys (keys identifying the relationship between different entities) are specified
Normalization occurs at this level