The chapters in Part 1 provided a starting point for your exploration of database technology and your understanding of the database development process. You broadly learned about database characteristics, DBMS features, the goals of database development, and the phases of the database development process. This chapter narrows your focus to the relational data model. Relational DBMSs dominate the market for business DBMSs. You will undoubtedly use relational DBMSs throughout your career as an information systems professional. This chapter provides background so that you may become proficient in designing databases and developing applications for relational databases in later chapters.
To effectively use a relational database, you need two kinds of knowledge. First, you need to understand the structure and contents of the database tables. Understanding the connections among tables is especially critical because many database retrievals involve multiple tables. To help you understand relational databases, this chapter presents the basic terminology, the integrity rules, and a notation to visualize connections among tables. Second, you need to understand the operators of relational algebra as they are the building blocks of most commercial query languages. Understanding the operators will improve your knowledge of query languages such as SQL. To help you understand the meaning of each operator, this chapter provides a visual representation of each operator and several convenient summaries.
