Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
1
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Answers to Review Questions
1. Why must a conceptual model be verified? What steps are involved in the verification process?
The verification of a conceptual model is crucial to a successful database design. The verification
process allows the designer to check the accuracy of the database design by:
Re-examining data and data transformations.
Enabling the designer to evaluate the design efficiency relative to the end user's and
system's design goals.
Keep in mind that, to a large extent, the best design is the one that serves the end-user
requirements best. For example, a design that works well for a manufacturing firm may not fit the
needs of a marketing research firm, and vice versa.
The verification process helps the designer to avoid implementation problems later by:
Validating the model's entities. (Remember the minimal data rule.)
Confirming entity relationships and eliminating duplicate, unnecessary, or improperly
defined relationships.
Eliminating data redundancies.
Improving the model's semantic precision to better represent real-world operations.
Confirming that all user requirements (processing, performance, or security) are met.
Verification is a continuous activity in any database design. The database design process is
evolutionary in nature: It requires the continuous evaluation of the developing model by examining
the effect of adding new entities and by confirming that any design changes enhance the model's
accuracy.
The verification process requires the following steps:
1. Identify the database's central entity.
The central entity is the most important entity in our database, and most of the other
entities depend on it.
2
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
2. Identify and define each module and its components.
The designer divides the database model into smaller sets that reflect the data needs of
particular systems modules such as inventory, orders, payroll, etc.
3. Identify and define each of the module's processes.
Specifically, this step requires the identification and definition of the database transactions
that represent the module's real-world operations.
3
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
4. Verify each of the transactions against the database.
2. What steps must be completed before the database design is fully implemented? (Make sure that
you list the steps in the correct sequence and discuss each step briefly.)
The DBLC, discussed in detail in Chapter 9, “Database Design,” constitutes a database's history,
tracing it from its conceptual design to its implementation and operation. We highly recommend
that the database designer follow the DBLC's steps carefully in order to ensure that the database will
properly meet all user and system requirements.
Before a database can be successfully implemented, the following steps must be completed:
1. Define the conceptual model's components: entities, attributes, domains, and relationships.
2. Normalize the database to ensure that all transitive dependencies are eliminated and that
each entity's attributes are solely dependent on its key attribute(s).
3. Verify the conceptual model to ensure that the proposed database will meet the system's
transaction requirements and that the end-user and systems requirements will be met.
The verification process will probably delete and/or create entities, attributes, and
relationships. It may also refine existing entities, attributes, and relationships.
4. Create the logical design which requires the definition of the table structures, using a
specific DBMS (relational, network or hierarchical). Logical design also includes, if necessary,
appropriate indexes and views.
5. Create the physical design to define access paths, including space allocation, storage group
creation, table spaces, and any other physical storage characteristic that is dependent on
the hardware and software to be used in the system's implementation.
6. Implement the design. Somehow, this last step seems to suffer from planning neglect, to
the detriment of the system's operation. Implementation, operation, and maintenance
plans must (at least) include careful definition and description of the activities required to
implement the database design:
loading and conversion
definition of database standards
system and procedures documentation: security, backup, and recovery
operational procedures to be followed by users
a detailed training plan
identification of responsibilities for operation and maintenance.
3. What major factors should be addressed when database system performance is evaluated?
Discuss each factor briefly.
4
Conceptual Design Verification, Logical Design, and Implementation
1
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
Answers to Review Questions
1. Why must a conceptual model be verified? What steps are involved in the verification process?
The verification of a conceptual model is crucial to a successful database design. The verification
process allows the designer to check the accuracy of the database design by:
Re-examining data and data transformations.
Enabling the designer to evaluate the design efficiency relative to the end user's and
system's design goals.
Keep in mind that, to a large extent, the best design is the one that serves the end-user
requirements best. For example, a design that works well for a manufacturing firm may not fit the
needs of a marketing research firm, and vice versa.
The verification process helps the designer to avoid implementation problems later by:
Validating the model's entities. (Remember the minimal data rule.)
Confirming entity relationships and eliminating duplicate, unnecessary, or improperly
defined relationships.
Eliminating data redundancies.
Improving the model's semantic precision to better represent real-world operations.
Confirming that all user requirements (processing, performance, or security) are met.
Verification is a continuous activity in any database design. The database design process is
evolutionary in nature: It requires the continuous evaluation of the developing model by examining
the effect of adding new entities and by confirming that any design changes enhance the model's
accuracy.
The verification process requires the following steps:
1. Identify the database's central entity.
The central entity is the most important entity in our database, and most of the other
entities depend on it.
2
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
2. Identify and define each module and its components.
The designer divides the database model into smaller sets that reflect the data needs of
particular systems modules such as inventory, orders, payroll, etc.
3. Identify and define each of the module's processes.
Specifically, this step requires the identification and definition of the database transactions
that represent the module's real-world operations.
3
, Appendix C The University Lab:
Conceptual Design Verification, Logical Design, and Implementation
4. Verify each of the transactions against the database.
2. What steps must be completed before the database design is fully implemented? (Make sure that
you list the steps in the correct sequence and discuss each step briefly.)
The DBLC, discussed in detail in Chapter 9, “Database Design,” constitutes a database's history,
tracing it from its conceptual design to its implementation and operation. We highly recommend
that the database designer follow the DBLC's steps carefully in order to ensure that the database will
properly meet all user and system requirements.
Before a database can be successfully implemented, the following steps must be completed:
1. Define the conceptual model's components: entities, attributes, domains, and relationships.
2. Normalize the database to ensure that all transitive dependencies are eliminated and that
each entity's attributes are solely dependent on its key attribute(s).
3. Verify the conceptual model to ensure that the proposed database will meet the system's
transaction requirements and that the end-user and systems requirements will be met.
The verification process will probably delete and/or create entities, attributes, and
relationships. It may also refine existing entities, attributes, and relationships.
4. Create the logical design which requires the definition of the table structures, using a
specific DBMS (relational, network or hierarchical). Logical design also includes, if necessary,
appropriate indexes and views.
5. Create the physical design to define access paths, including space allocation, storage group
creation, table spaces, and any other physical storage characteristic that is dependent on
the hardware and software to be used in the system's implementation.
6. Implement the design. Somehow, this last step seems to suffer from planning neglect, to
the detriment of the system's operation. Implementation, operation, and maintenance
plans must (at least) include careful definition and description of the activities required to
implement the database design:
loading and conversion
definition of database standards
system and procedures documentation: security, backup, and recovery
operational procedures to be followed by users
a detailed training plan
identification of responsibilities for operation and maintenance.
3. What major factors should be addressed when database system performance is evaluated?
Discuss each factor briefly.
4
