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Text A: Data Modeling

Key considerations in organizing data in a database include determining what data is to be collected in the database, who will have access to it, and how they might wish to use the data. Based on these determinations, a database can then be created. Building a database requires two different types of designs: a logical design and a physical design.

The logical design of a database shows an abstract model of how the data should be structured and arranged to meet an organization’s information needs. The logical design of a database involves an orderly fashion. Because databases provide both input and output for information systems throughout a business, users from all functional areas should assist in creating the logical design to ensure that their needs are identified and addressed.

Physical database design starts from the logical database design and fine-tunes it for performance and cost considerations (e.g. improved response time, reduced storage space, lower operating cost0. The person identified to fine-tune the physical design must have an in-depth knowledge of the DBMS to implement the database. For example, the logical database design may need to be altered so that certain data entities are combined, summary totals are carried in the data records rather than calculated from elemental data, and some data attributes are repeated in more than one data entity. These are examples of planned data redundancy. It is done to improve the system performance so that the user reports or queries can be created more quickly.

1. Read the questions and circle the correct answer.

1. How many types of design does building a database require?

a) two different types of designs; b) three different types of designs; c) only one type of design;

2. Who must have an in-depth knowledge of the DBMS to implement the database?

a) the person identified to fine-tune the logical design; b) the person identified to fine-tune the physical design; c) the person responsible to implement the logical design;

3. What does the logical design of a database involve?

a) an orderly fashion; b) modern fashion; c) structure fashion

4. Which users should assist in creating the logical design to ensure that their needs are identified and addressed?

a) programmers from all functional areas; b) users from all structural areas; c) users from all functional areas

5. What can improve the system performance?

a) scalability; b) planned data redundancy; c) creation of domain

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