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12.8 Describe how strong and weak entity types differ and provide an example of each.

A strong entity type is an entity type that is not existence-dependent on some other entity type
A weak entity type is an entity type that is existence-dependent on some other entity type.


Strong entity weak entity
Client is strong entity because it already has primary key and doesn’t depend on any other entity, but the reference is weak entity because depends on client entity and doesn’t have primary key. (Section 12.4).

12.11 You are required to create a conceptual data model of the data requirements for a company that
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A design methodology is a structured approach that uses procedures, techniques, tools, and documentation aids to support and facilitate the process of design.

16.2 Describe the main phases involved database design.
Database design is made up of three main phases: logical and physical database design.
Conceptual database design: the process of constructing a model of the data used in an enterprise, independent of all physical consideration. It begin with creating conceptual data model for the enterprise that is entirely independent of implementation details.
Logical database design is the process of constructing a model of the data used in a company based on a specific data model, but independent of a particular DBMS and other physical considerations.
In the logical database design phase we build the logical representation of the database, which includes identification of the important entities and relationships, and then translate this representation to a set of tables. The logical data model is a source of information for the physical design phase, providing the physical database designer with a vehicle for making tradeoffs that are very important to the design of an efficient database.
Physical database design is the process of producing a description of the implementation of the database on secondary storage; it describes the base tables, file organizations, and indexes used to achieve efficient access to the data, and any

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