1.1 OUTSTANDING FEATURES OF THIS BOOK 1) This book covers both fundamental and advanced Java database programming techniques to help both beginning and experienced students as well as programmers. 2) A sample database, CSE _ DEPT, which represents an example computer science depart-ment and is built with Oracle 18c Express […]
Category: Foreign Keys and Referential Integrity
HOW THIS BOOK IS ORGANIZED AND HOW TO USE THIS BOOK – Introduction
1.4 HOW THIS BOOK IS ORGANIZED AND HOW TO USE THIS BOOK This book is designed for both college students who are new to database programming with Java and professional database programmers who have some experience on this topic. Chapters 2 and 3 provide the fundamentals on database structures and […]
Integrated Databases – Introduction to Databases
2.1.2 Integrated Databases A better alternative to a file processing system is an integrated database approach. In this environ-ment, all data belonging to an organization is stored in a single database. The database is not a mere collection of files; there is a relation between the files. Integration implies a […]
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 […]
Tables – Introduction to Databases
2.8.1.2 Tables Before you can create a Table in Access, you must create a database container and give it a name with the extension. mdb. Database creation is simple process and is explained in detail with an example later in this chapter. Suffice it to say that a Table is […]
Data Files – Introduction to Databases
2.8.2.1 Data Files A data file is a conglomeration of objects, which includes Tables, keys, views, stored procedures and others. All these objects are necessary for the efficient operation of the database. 2.8.2.2 Tables The data in a relational database resides in Tables. These are the building blocks of the […]
Keys and Relationships – Introduction to Databases
2.8.2.5 Keys and Relationships A primary key is created for each Table in the database to efficiently access records and to ensure entity integrity. This implies that each record in a Table is unique in some way. Therefore, no two records can have the same primary key. The primary key […]
Transaction Log Files – Introduction to Databases
2.8.2.7 Transaction Log Files A transaction is a logical group of SQL statements that carry out a unit of work. Client server databases use log files to keep track of transactions that are applied to the database. For example, before an update is applied to a database, the database server […]