Welcome to Lesson one of Module six on Notation for Entity Relationship Diagrams. I'm gonna start with an important motivational question about database development. Why is database development challenging and exciting? Module six is a major shift from the previous modules. The previous modules emphasized query formulation skills that are concrete, as you can evaluate statements for correctness and non-redundancy. In contrast, database development skills covered in the coming modules are more ambiguous, but provide more opportunity for creative problem solving. Query formulation is a commonly applied skill as organizations use databases more than develop new databases or make major revisions to existing databases. However, you have the opportunity to have a longer term impact on organization through application of database development skills. The objectives in this lesson involve a broad focus on the database development process to provide a context for skill development. This context will help you to reflect on the skills you learn in other lessons of this module. You should be able to explain the goals of database development, in the position of the skills covered in this module, in the database development process. Databases are essential components of many information systems. The role of a database is to provide a long-term memory for an information system. The long-term memory contains entities and relationships. For example, the database for a student loan system contains data about students, loans, and payments so that the statements, cash disbursements, and delinquency notices can be generated. Databases are not the only components of information systems. Information systems also contain people, procedures, input data, output data, software and hardware. Thus, developing an information system involves more than developing a database. However, in many development efforts for business information systems, database development is the most important activity. For business information systems the models for processes and environment interaction are usually created after the data model. Thus, the remaining modules in this course emphasize database development concept and skills. Broadly, the goal of database development is to create a database that provides an important resource for an organization. To fulfill this broad goal, a database should provide a vocabulary for a large community of users, support organizational policies, contain high-quality data, and provide efficient access. Achieving a common vocabulary that facilitates communication is not easy. Developing a database requires compromise to satisfy a large community of users. In some sense, a good database designer shares some characteristics with a good politician. A good politician often finds solutions with which everyone finds something to agree and unfortunately disagree. In establishing a common vocabulary, a good database designer also finds similar imperfect solutions. Forging compromises can be difficult. But the results can improve productivity, customer satisfaction, and other measures of organizational performance. A database contains business rules to support organizational policies. Defining business rules is the essence of defining semantics or meaning of a database. For example, in an order entry system, an important rule is an order must precede a shipment. A database can contain an integrity constraint to support this rule. Defining business rules enables a database to actively support organizational policies. This active role contrasts with a more passive role that databases have in establishing a common vocabulary. 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. Even if the other design goals are met, a slow performing database will not be used. Thus, finding in an efficient implementation is paramount. However, an efficient implementation should respect the other goals as much as possible. An efficient implementation that compromises the meaning of the database or data quality may be rejected by database users. The goal of the database development process is to produce an operational database for an information system. To produce an operational database, you needed to find data models and populate that is supplied with data, the database. This diagram shows important phases in the database development process. The first two phases are concerned with the information content of the database. While the last two phases are concerned with efficient implementation. This course covers the conceptual data modeling and logical database design phases. Module six and seven, focus on a notation for entity relationship diagrams or ERD's. Modules eight and nine, emphasize the process of conceptual data modeling using the ERD notation covered in module six and seven. The details of distributed database design and physical database design phases, depend on the processing architecture that is transaction processing versus business intelligence processing and the DBMS. No details in this course are provided on the last two phases. The third course, Relational Database Support for Data Warehouse Processing, covers physical design for data warehouses. Now, let's wrap up lesson one about database development goals. This lesson has provided broad coverage of the database development process to give you a context to the details in other lessons. You should remember that a database is an essential part of an information system, often the most important artifact for business information systems. In the remaining modules of this course, the concepts and skills that you acquire will apply to the goals of developing a common vocabulary, creating business roles, and ensuring data quality. The remaining lessons in this module and the following module emphasize the notation of entity relationship diagrams. This prerequisite knowledge for performing conceptual data modeling. In answer to the opening question, database development is an exciting and challenging activity. Database development is somewhat subjective, giving you lots of opportunity for creative problem solving. You can facilitate major change in an organization through developing databases that provide common vocabularies and business rules to unify different parts of an organization.
