represent entities and their relationshiops." (pg.81, Jessup, Valacich & Wade) It has four types of organizations, there are hierarchical model, network model, relational model and object model. According to database model a data modeling language is a schema of each database. A DBMS gives one or more of the four data model and its optimal structure depend on the application's data and applicaton's requirements. Data structures are fields, records, files and objects that is designed to handle a large collection of data stored on a permanent data storage device.A database query language is a report writer which allow the users to work toghether with database, analyze its data and update its data with the users privileges. So security of the database is proctected and prevents unauthorized users from viewing the confidential information. Users have their own passoward to access to the entire database or subschemas. "For example, an employee database can contain all the data about an individual employee, but one group of users may be authorized to view only payroll data, while others are allowed access to only work history and medical data." (wikipedia.org) A database transaction mechanism is make sure the order of data integrity and faults. It also maintains the integrity of the database. This system protects the records from coloning. For example, only one studendt identification number for one student. No two students with the same student ID number. This specific ID number called unique key in database and each record of an entity must have one unique key in order distinguish between records.
DBMS Softwares
1. DataEase: DataEase is data-intensive software applications for personal computers. It was created by software develpers Arun Gupta and Joseph Busch in 1980. There are two different product in DataEase: DataEase for DOS and DataEase for Windows.
2. ADABAS: ADABAS is a software AG’s primary database management system and it provides an efficient access to data and maintaining the integrity of the database. It is an application that needs very high volumes of data processing and high transaction processing environments.
3. Microsoft Office Access: Access is a relational database management system from Microsoft and software development tools. It stores data in its own format based on the access jet database engine.
Reference: wikipedia.org and garret.ru/goods.html
figure from: http://indsgroup.com/EMS1.GIF
more infor visit: http://www.doeacc.edu.in/jsp/syllabus/pdf/a7.pdf
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