Seventh Quiz : NORMALIZATION

Database Normalization

Normalization process is the establishment of the database structure so that most of the ambiguity can be removed. Normalization stage, starting from the most mild (1NF) to most stringent (5NF) usually only reach the level of 3NF or BCNF because already sufficient to generate the table-a table of good quality.

Why do normalization?
1. Optimizing table structures
2. Increase speed
3. The income data is the same
4. More efficient of storage media
5. Reduce redundancy
6. Avoid anomalies (insertion anomalies, deletion anomalies, update anomalies).
7. Improved data integrity

A table saying good (efficient) or if normal meet 3 criteria:
1. If there is decomposition (decomposition) table, it must be guaranteed safe decomposition (Lossless-Join Decomposition). That is, after the table is described for a new table-table, the table-table can  generate a new table with the same exact.
2. Maintain dependence on the functional changes in data (Dependency preservation).
3. Does not violate Boyce-Code Normal Form (BCNF)

If the three criteria (BCNF) can not be met, then at least the table does not violate the Normal Form of the third stage (3rd Normal Form / 3NF).

Fifth Quiz : DATA FLOW DIAGRAM (DFD)

DEFINITION
Structured approach to the design starting from early 1970. Structured approach, complete with tools and needed techniques in the development of the system, so that the final results of the system will be developed in a system with well defined structure and clear.

Through structured, complex problems can be solved in the organization and results of the system will easy to maintain, flexible, more satisfied users, have any documentation of good, timely, according to the budget cost of development, can improve productivity and quality will be better (free error).

DFD is a logical data model or process that is made to describe the origin of the data and the destination where the data out of the system, where data is stored, the process that produces the data and the interaction between the data stored and the process is imposed on data.

DFD are often used to describe a system that already exists or the new system will be developed logically without considering the physical environment where the data flows, or where data are stored and the user is easy to understand to understand the field of computer systems that will be done.

DFD is a tool that system design-oriented data flow with the concept of decomposition can be used for the delineation and analysis of system design that is easily communicated to the system by the professional user and the program.