Database system
From ArticleWorld
A database system is a computerized record-keeping system that stores information which users can access and modify. A database system can store any kind of information that is relevant to the person or business concerned. Even complex data such as images, sound and video are supported in modern database systems.
Contents |
Major components
A database system consists of four main components, viz. data, hardware, software and users. These components are explained briefly below:
Data
The interrelated facts or information stored in a database system are collectively known as data.
Hardware
The hardware system mainly consists of the processor(s) and primary and secondary storage. Primary storage refers to those storage media that the processor directly operates upon. Magnetic disks, magnetic tapes and optical disks are the most common secondary storage devices. Data in secondary storage cannot be directly operated upon by the processor; they need to be first copied into primary storage.
Software
The software is used to run the hardware. The most important software is the Database Management System (DBMS). The DBMS contains:
- Programming languages for querying and maintaining the database (typically SQL)
- CASE tools
- Application Programming Interfaces (APIs) to allow data to be exchanged with external software packages
- Database administration tools to monitor database usage and performance
Users
There are four broad categories of database users:
- Database administrators (DBAs): The DBA is responsible for the maintenance and performance of the system. This includes granting database access to users and checking to see whether any new hardware or software is required.
- Database designers: These are responsible for deciding what data to store. Database designers also decide on the data structures for the representation and storage of data.
- Software engineers: This category can be divided into two groups: system analysts and application programmers. System analysts gather the requirements for a new database system from end-users and develop technical specifications which they provide to application programmers. On the basis of these specifications, application programmers write database application programs in programming languages such as COBOL, C++ or JAVA.
- End users: These are people whose jobs require access to the database system. End users may query or modify the database using either a command-line interface or a graphical user interface (GUI).