Mobile Transaction Processing System

Database And Transaction Concepts

A database is a collection of data items that is gathered over a period of time, and safety stored for further examination or analysis. A database is usually accompanied by a data structure and a set of constraint rules that specify what information (Maassen, Nieuwpoort, Veldema, Bal and Plaat 1999) a data item represents. For example, in an employee database, the employee age is an integer number and must be greater than eighteen and less than sixty five. A database state is a collection of all the stored data values of all the data items in the database at a specific time. A consistent state of a database is a database state in which all the data values fulfill all the constraint rules of the database. A set of operations is usually provided to support users in retrieving or modifying data items in the database. These provided operations can be simple, for example read and write operations, or more complex operations, for example deletion or modification operations. To assist users to perform much more complex operations rather than reading from and writing to the database, a piece of specialized software called a database management system (DBMS) is accommodated to the database. In general, a DBMS not only provides an easy-to-use and friendly interface to users for accessing and manipulating the database, but also manages all the database operations. In addition, the DBMS also protects the database from unauthorized users.