Data and Databases
This chapter covers the concepts of data and databases. Businesses are becoming more and more "data-driven"; understanding how data is collected, stored, and managed is essential for anyone wanting to succeed in business. Pay special attention to the sections on data warehouses and data mining, as they provide examples of how companies use data strategically.
Data Models and Relational Databases
Databases can be organized in many different ways by using different models. The data model of a database is the logical structure of data items and their relationships. There have been several data models. Since the 1980s, the relational data model has been popularized. Currently, relational database systems are commonly used in business organizations with few exceptions. A relational data model is easy to understand and use.
In a relational database, data is organized into tables (or relations). Each table has a set of fields which define the structure of the data stored in the table. A record is one instance of a set of fields in a table. To visualize this, think of the records as the rows (or tuple) of the table and the fields as the columns of the table.
In the example below, we have a table of student data, with each row representing a student record , and each column representing one filed of the student record. A special filed or a combination of fields that determines the unique record is called primary key (or key). A key is usually the unique identification number of the records.
Rows and columns in a table