DATABASE DEVELOPMENT IN DBMS, Slides of Database Management Systems (DBMS)

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Database Systems

Lecture

Topic: Introduction to Database Development

Instructor: Lecturer Ayesha Naseer

Learning Objectives

• List the steps in the information systems life cycle.
• Describe the role of databases in an information system.
• Explain the goals of database development.
• Understand the relationships among phases in the database development process.

Example of Information System for Student Loan Processing

 Databases are essential components of many information systems.

 The role of a database is to provide long-term memory for an information system.

The long-term memory contains entities and relationships.

Goals of Database Development Develop a Common Vocabulary A database provides a common vocabulary for an organization. Before a common database is implemented, different parts of an organization may have different terminology. For example, there may be multiple formats for addresses, multiple ways to identify customers, and different ways to calculate interest rates. After a database is implemented, communication can improve among different parts of an organization. Thus, a database can unify an organization by establishing a common vocabulary. Define the Meaning of Data A database contains business rules to support organizational policies. Defining business rules is the essence of defining the semantics or meaning of a database. For example, in an order entry system, an important rule is that an order must precede a shipment. The database can contain an integrity constraint to support this rule. Defining business rules enables the database to actively support organizational policies. Ensure Data Quality The importance of data quality is analogous to the importance of product quality in manufacturing. Poor product quality can lead to loss of sales, lawsuits, and customer dissatisfaction. Because data are the product of an information system, data quality is equally important. Poor data quality can lead to poor decision making about communicating with customers, identifying repeat customers, tracking sales, and resolving customer problems. For example, communicating with customers can be difficult if addresses are outdated or customer names are inconsistently spelled on different orders.

Database Development Process

Phases of Database development

1. Conceptual Data Modeling

The conceptual data modeling phase uses data requirements and produces entity

relationship diagrams (ERDs) for the conceptual schema and for each external

schema. Data requirements can have many formats such as interviews with users,

documentation of existing systems, and proposed forms and reports. The conceptual

schema should represent all the requirements and formats.

Phases of Database development

3. Distributed Database Design The distributed database design phase marks a departure from the first two phases. The distributed database design and physical database design phases are both concerned with an efficient implementation. In contrast, the first two phases (conceptual data modeling and logical database design) are concerned with the information content of the database. Distributed database design involves choices about the location of data and processes so that performance can be improved.
4. physical Database Design The physical database design phase, like the distributed database design phase, is concerned with an efficient implementation. Unlike distributed database design, physical database design is concerned with performance at one computer location only. If a database is distributed, physical design decisions are necessary for each location.

Cross Checking with Application Development The database development process does not exist in isolation. Database development is conducted along with activities in the systems analysis, systems design, and systems implementation phases. The conceptual data modeling phase is performed as part of the systems analysis phase. The logical database design phase is performed during systems design. The distributed database design and physical database design phases are usually divided between systems design and systems implementation. Most of the preliminary decisions for the last two phases can be made in systems design. However, many physical design and distributed design decisions must be tested on a populated database. Thus, some activities in the last two phases occur in systems implementation.

Closing Thoughts  This Lecture initially described the role of databases in information systems and the nature of the database development process.  Information systems are collections of related components that produce data for decision making. Databases provide the permanent memory for information systems.  Development of an information system involves a repetitive process of analysis, design, and implementation. Database development occurs in all phases of systems development.  Because a database is often a crucial part of an information system, database development can be the dominant part of information systems development.  Development of the processing and environment interaction components are often performed after the database development.  Cross-checking between the database and applications is the link that connects the database development process to the information systems development process.  After presenting the role of databases and the nature of database development, this chapter described the goals, phases, and tools of database development.  The goals emphasize both the information content of the database as well as efficient implementation.  The phases of database development first establish the information content of the database and then find an efficient implementation.  The conceptual data modeling and logical database design phases involve the information content of the database.  The distributed database design and physical database design phases involve efficient implementation.

Resources

 Chapter 1, Michael V. Mannion., Database Design, Application Development, and

Administration, , Mc Graw Hill Publishers, 3

rd

edition,

 Chapter 1, Avi Silberschatz, Henry F. Korth, S. Sudarshan , Database Systems

Concepts , Mc Graw Hill Publishers, 7

th

edition

 Chapter 1, Elmasri and Navathe. Fundamentals of Database Systems. Addison-

Wesley, 7

th

edition, 2007.