Components of Database Systems
DBMS have several components, each performing very significant tasks in the database
management system environment.
i. Software: This is the set of programs used to control and manage the overall database. This includes the DBMS software itself, the Operating System, the network software being used to share the data among users, and the application programs used to access data in the DBMS.
ii. Hardware: Consists of a set of physical electronic devices such as computers, I/O devices, storage devices, etc., this provides the interface between computers and the real-world systems.
iii. Data: DBMS exists to collect, store, process and access data, the most important component. The database contains both the actual or operational data and the metadata.
iv. Procedures: These are the instructions and rules that assist on how to use the DBMS, and in designing and running the database, using documented procedures, to guide the users that operate and manage it.
v. Database Access Language: This is used to access the data to and from the database, to enter new data, update existing data, or retrieve required data from databases. The user writes a set of appropriate commands in a database access language, submits these to the DBMS, which then processes the data and generates and displays a set of results into a user readable form.
• Data Manipulation Languages – this is a software program that instructs the database to perform a specific task e.g. retrieving information from the database
• Data definition Languages – this is a software program used to define the data from the database. It also used for giving authorization rights.
vi. Query Processor: This transforms the user queries into a series of low-level instructions. This reads the online user’s query and translates it into an efficient series of operations in a form capable of being sent to the run time data manager for execution. vii. Run Time Database Manager: Sometimes referred to as the database control system, this
is the central software component of the DBMS that interfaces with user-submitted application programs and queries, and handles database access at run time. Its function is to convert operations in user’s queries. It provides control to maintain the consistency, integrity and security of the data.
viii. Data Manager: Also called the cache manger, this is responsible for handling of data in the database, providing a recovery to the system that allows it to recover the data after a failure.
ix. Database Engine: The core service for storing, processing, and securing data, this provides controlled access and rapid transaction processing to address the requirements of the most demanding data consuming applications. It is often used to create relational databases for online transaction processing or online analytical processing data.
x. Data Dictionary: This is a reserved space within a database used to store information about the database itself. A data dictionary is a set of read-only table and views, containing the different information about the data used in the enterprise to ensure that database representation of the data follow one standard as defined in the dictionary.
Characteristics of Data Dictionary
• A documentation of all data items within the database
• Definition of all data items
• Description of all data items
• Removal of redundant in data items
• Documentation of relationships between the data items
xi. Report Writer: Also referred to as the report generator, it is a program that extracts information from one or more files and presents the information in a specified format. Most report writers allow the user to select records that meet certain conditions and to display selected fields in rows and columns, or also format the data into different charts.