James Bond
Exercise Solution – Day 8
1. Answer the following questions.
1A. What do the acronyms SDLC and DBLC mean, and what do they portray?
SDLC = Systems Development Life Cycle (SDLC)
DBLC = Database Life Cycle
1B. What is the relationship between the SDLC and the DBLC?
The SDLC traces the history (life cycle) of an information system. The DBLC traces the history (life cycle) of a database system. Since we know that the database serves the information system, it is not surprising that the two life cycles conform to the same basic phases.
1C. What basic database design strategies exist, and how are such strategies executed?
There are two basic approaches to database design: top-down and bottom-up.
Top-down design begins by identifying the different entity types and the definition of each entity's attributes. In other words, top-down design:
• starts by defining the required data sets and then
• defines the data elements for each of those data sets.
Bottom-up design:
• first defines the required attributes and then
• groups the attributes to form entities.
Although the two methodologies tend to be complementary, database designers who deal with small databases with relatively few entities, attributes, and transactions tend to emphasize the bottom-up approach. Database designers who deal with large, complex databases usually find that a primarily top-down design approach is more appropriate. In spite of the frequent arguments concerning the best design approach, perhaps the top-down vs. bottom-up distinction is quite artificial.
1D. What is the minimal data rule in conceptual design? Why is it important?
The minimal data rule specifies that all the data defined in the data model are actually required to fit present and expected future data requirements. This rule may be phrased as
All that is needed is there, and all that is there is needed.
1E.
1. Answer the following questions.
1A. What do the acronyms SDLC and DBLC mean, and what do they portray?
SDLC = Systems Development Life Cycle (SDLC)
DBLC = Database Life Cycle
1B. What is the relationship between the SDLC and the DBLC?
The SDLC traces the history (life cycle) of an information system. The DBLC traces the history (life cycle) of a database system. Since we know that the database serves the information system, it is not surprising that the two life cycles conform to the same basic phases.
1C. What basic database design strategies exist, and how are such strategies executed?
There are two basic approaches to database design: top-down and bottom-up.
Top-down design begins by identifying the different entity types and the definition of each entity's attributes. In other words, top-down design:
• starts by defining the required data sets and then
• defines the data elements for each of those data sets.
Bottom-up design:
• first defines the required attributes and then
• groups the attributes to form entities.
Although the two methodologies tend to be complementary, database designers who deal with small databases with relatively few entities, attributes, and transactions tend to emphasize the bottom-up approach. Database designers who deal with large, complex databases usually find that a primarily top-down design approach is more appropriate. In spite of the frequent arguments concerning the best design approach, perhaps the top-down vs. bottom-up distinction is quite artificial.
1D. What is the minimal data rule in conceptual design? Why is it important?
The minimal data rule specifies that all the data defined in the data model are actually required to fit present and expected future data requirements. This rule may be phrased as
All that is needed is there, and all that is there is needed.
1E.