Unit 1: Introduction to Modern Database Systems
Different databases serve different purposes; each one is dependent upon both deployment environment and different types of user interactions. In this unit, we will ask a number of questions pertaining to databases: What are some database environments and user types? How can the database management system ensure control over data integrity, avoid data redundancy, and secure data, while at the same allowing interactions with different user types? In answering these questions, we will identify and determine the characteristics of databases, their many deployment environments, and the different categories of users that interact with them.
Completing this unit should take you approximately 5 hours.
Upon successful completion of this unit, you will be able to:
- explain the difference between data and information and give examples of each;
- compare and contrast file processing systems and database systems, showing how problems of file processing systems are addressed by features of databases;
- describe what a database management system (DBMS) is and demonstrate how it functions; and
- compare the various database models.
1.1: Characteristics of Databases
Read chapter 1, which begins by discussing fundamental data concepts. The study of databases is an extension of the study of data in programming. The study of databases as a discipline was motivated by a variety of factors: the increasing size and complexity of software systems, the need to share data, and the need to be able to maintain and secure data effectively.
Data is a collection of symbols used to represent numbers, text, pictures, videos, audio, and so on. How this data is represented gives the meaning (or semantics) for the symbols. Additional semantics are provided by the relationships that data has with other data. In programming, the semantics of data is provided by program documentation, as well as the programming language used to create the program. In databases, the semantics of the data is provided by a data model, which includes the representation of the data, relationships among the data, and metadata (which is data that defines other data).
Semantics makes data useful, and we define useful data as information. Sometimes, the terms 'data' and 'information' appear as synonyms. However, they are different: all information is data, but not all data is information. The type and amount of semantics determines the usefulness of some given data. Usefulness is also relative to a given user. Data may not be useful to some users, but very useful to others.
Identifying data and information and organizing them into a data model typically occurs in software requirements analysis and design. Current work in the field of databases addresses techniques that support building and storing data models, and using them to discover meaning (or information) in large volumes of data.
Read chapters 2 and 3. Chapter 2 explores the fundamental concepts of databases and their properties. Chapter 3 discusses the characteristics of databases that give them their unique advantages. From a database development perspective, these characteristics are known as "requirements". Be sure to complete the short exercises at the end of each chapter.
Read chapter 1, which begins with a description of database management systems (DBMS). DBMSes are software systems that enable and support the use of databases.
1.2: Database Environments
Read this article on the types of databases and their functions. The article introduces a data model, which is the conceptual design for a database from a development perspective.
Read chapters 4 and 5, which discuss the types of data models, their properties, and their levels of abstraction: external, conceptual, internal, and physical. We will later refer to these levels of abstraction as 'schema levels'.
Read chapter 2, which continues the top-down discussion on DBMSes. It describes the elements of a DBMS, functional requirements and necessary characteristics (which corresponds to the external view of the 3-level schema architecture perspective), design (which corresponds to the conceptual model view), and implementation (which corresponds to the internal/physical model view). It also gives an overview of database and DBMS processes, including planning, development techniques and methods, roles and responsibilities, stakeholders, and database and DBMS maintenance and configuration control (which is how to control changes to the database or DBMS).
1.3: Classifying Database Management Systems
Read chapter 6, which takes a bottom-up approach, going from data to databases to DBMSes. Previous chapters addressed data and databases, while this chapter discusses DBMSes and classifies them using several criteria.
This course primarily covers traditional databases, but this article gives an overview of some non-traditional databases and classifies non-SQL databases according to their operational model. Non-SQL databases are schema-less, and not based on a single data model.
Read this article on how to classify traditional and non-traditional databases based on internal and implementation models.
Unit 1 Assessment
- Receive a grade
Take this assessment to see how well you understood this unit.
- This assessment does not count towards your grade. It is just for practice!
- You will see the correct answers when you submit your answers. Use this to help you study for the final exam!
- You can take this assessment as many times as you want, whenever you want.