2.2 DEVELOPING A DATABASE The database development process may follow a classical systems development life cycle. 1) Problem Identification—Interview the user, identify user requirements. Perform preliminary analysis of user needs.2) Project Planning—Identify alternative approaches to solving the problem. Does the project need a database? If so, define the problem. Establish […]
Year: 2023
A SAMPLE DATABASE – Introduction to Databases
2.3 A SAMPLE DATABASE We will use a sample database, CSE _ DEPT, to illustrate some essential database concepts. Tables 2.1~2.5 show sample data Tables stored in this database. FIGURE 2.1 Records and fields in a Table. The data in CSE _ DEPT database is stored in five Tables—LogIn, Faculty, […]
Relational Data Model – Introduction to Databases
2.3.1 Relational Data Model A data model is like a blueprint for developing a database. It describes the structure of the database and various data relationships and constraints on the data. This information is used in building Tables and keys and defining relationships. A relational model implies that a user […]
IDENTIFYING KEYS – Introduction to Databases
2.4 IDENTIFYING KEYS 2.4.1 Primary Key and Entity Integrity An attribute that uniquely identifies one and only one instance of an entity is called a primary key. Sometimes a primary key consists of a combination of attributes. It is referred to as a composite key. The entity integrity rule states […]
Foreign Keys and Referential Integrity – Introduction to Databases
2.4.3 Foreign Keys and Referential Integrity Foreign keys are used to create relationships between Tables. It is an attribute in one Table whose values are required to match those of primary key in another Table. Foreign keys are created to enforce referential integrity, which states that you may not add […]
DEFINE RELATIONSHIPS – Introduction to Databases
2.5 DEFINE RELATIONSHIPS 2.5.1 Connectivity Connectivity refers to the types of relationships that entities can have. Basically, the relationship can be one-to-one, one-to-many and many-to-many. In ER diagrams, these are indicated by placing 1, M orN at one of the two ends of the relationship diagram. Figures 2.2–2.5 illustrate the […]