If some cardinality ratio or dependency cannot be determined from the requirements, the users must be questioned further to determine these structural constraints
DBMS typically includes a database security and authorization subsystem that is responsible for ensuring the security of portions of a database against unauthorized access
Self-describing nature of a database system Insulation between programs and data, and data abstraction Support of multiple views of the data Sharing of data and multiuser transaction processing
The basic structure of an SQL query consists of three clauses: select, from, and where.
Entity types that do not have key attributes of their own are called weak entity types. In contrast,regular entity types that do have a key attribute—which include all the examples discussed so far—are called strong entity types
The basic notation for specialization/generalization is to connect the subclasses by vertical lines to a horizontal line, which has a triangle connecting the horizontal line through another vertical line to the superclass. A blank triangle indicates a specialization/generalization with the disjoint ...
we discuss differences between specialization/generalization lattices (multiple inheritance) and hierarchies (single inheritance), and elaborate on the differences between the specialization and generalization processes during conceptual database schema design. We discuss constraints that apply ...
A super-key is a set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple in the relation.
There are several implicit relationships among the various entity types. In fact, whenever an attribute of one entity type refers to another entity type, some relationship exists. For example, the attribute Manager of DEPARTMENT refers to an employee who manages the department; the attribute
A database system is partitioned into modules that deal with each of the responsibilities of the overall system. The functional components of a database system can be broadly divided into the storage manager and the query processor components.
The typical method of enforcing discretionary access control in a database system is based on the granting and revoking of privileges. Let us consider privileges in the context of a relational DBMS.
This chapter discusses techniques for securing databases against a variety of threats. It also presents schemes of providing access privileges to authorized users.
The specialization relationship may also be referred to as a superclass-subclass relationship. Higher- and lower-level entity sets also may be designated by the terms superclass and subclass, respectively. The person entity set is the superclass of the employee and student subclasses.
A database-management system (DBMS) is a collection of interrelated data and a set of programs to access those data.
The UML methodology is being used extensively in software design and has many types of diagrams for various software design purposes. We only briefly present the basics of UML class diagrams here, and compare them with ER diagrams
Sensitivity of data is a measure of the importance assigned to the data by its owner, for the purpose of denoting its need for protection. Some databases contain only sensitive data while other databases may contain no sensitive data at all.
Researchers have developed several data-models to deal with these application domains, including object-based data models and semi-structured data models.
The term data mining refers loosely to the process of semi-automatically analysing large databases to find useful patterns.
The rapid advancement of the use of information technology (IT) in industry, government, and academia raises challenging questions and problems regarding the protection and use of personal information. Questions of who has what rights to information about individuals for which purposes become more i...
Databases are widely used in enterprises, banking and finance, universities, airlines, telecommunication, etc.
A relational database is based on the relational model and uses a collection of tables to represent both data and the relationships among those data.