Active database

An active databases is a database that includes active rules, mostly in the form of ECA rules. Active database systems enhance traditional database functionality with rule processing capabilities, providing a uniform and efficient mechanism for many database system applications. Among these applications are integrity constraints, views, authorization, statistics gathering, monitoring and alerting, knowledge-based systems, expert systems, and workflow management. This significant collection focuses on the most prominent research projects in active database systems. The project leaders for each prototype system provide detailed discussions of their projects and the relevance of their results to the future of active database systems..

lets consider some example to illustrate these concepts.The example are based on a much simplified variation of a COMPANY database application,which is shown in following figure with employee having a name(NAME), social security number(SSN), salary (SALARY),department to which they are currently assigned (DNO,a foreign key DEPARTMENT), and a direct supervisor(SUPERVISOR_SSN, A (recursive) foreign key to EMPLOYEE0. For this example,we assume that null is allowed DNO, indicating that an employee may be temporarily unassigned to any department.each department has a DNAME,number(DNO), the total salary of all employee assigned to the department(TOTAL_SAL),and a manager(MANAGER_SSN,a foreign key to EMPLOYEE).

event- the event that triggers the rule.