Databases and Database Users in dbms
Databases and database systems are an essential component of life in modern society: most of us encounter several activities every day that involve some interaction with a database
- Databases and database technology have a major impact on the growing use of computers. It is fair to say that databases play a critical role in almost all areas where computers are used, including business, electronic commerce, engineering, medicine, genetics, law, education, and library science
- The word database is so commonly used that we must begin by defining what a database is. Our initial definition is quite general.
- A database is a collection of related data. By data, we mean known facts that can be recorded and that have implicit meaning. For example, consider the names, telephone numbers, and addresses of the people you know.
- You may have recorded this data in an indexed address book or you may have stored it on a hard drive, using a personal computer and software such as Microsoft Access or Excel.
- This collection of related data with an implicit meaning is a database.
- The preceding definition of database is quite general; for example, we may consider the collection of words that make up this page of text to be related data and hence to constitute a database.
- . However, the common use of the term database is usually more restricted.
- A database management system (DBMS) is a collection of programs that enables users to create and maintain a database.
- The DBMS is a general-purpose software system that facilitates the processes of defining, constructing, manipulating, and sharing databases among various users and applications.
- Defining a database involves specifying the data types, structures, and constraints of the data to be stored in the database.
- The database definition or descriptive information is also stored by the DBMS in the form of a database catalog or dictionary; it is called meta-data.
- Constructing the database is the process of storing the data on some storage medium that is controlled by the DBMS.
- Manipulating a database includes functions such as querying the database to retrieve specific data, updating the database to reflect changes in the miniworld, and generating reports from the data. Sharing a database allows multiple users and programs to access the database simultaneously.
A database has the following implicit properties:
- A database represents some aspect of the real world, sometimes called the miniworld or the universe of discourse (UoD). Changes to the miniworld are reflected in the database
- A database is a logically coherent collection of data with some inherent meaning. A random assortment of data cannot correctly be referred to as a database.
- A database is designed, built, and populated with data for a specific purpose. It has an intended group of users and some preconceived applications in which these users are interested.
- In any organization where many people use the same resources, there is a need for a chief administrator to oversee and manage these resources.
- In a database environment, the primary resource is the database itself, and the secondary resource is the DBMS and related software.
- Administering these resources is the responsibility of the database administrator (DBA).
- The DBA is responsible for authorizing access to the database, coordinating and monitoring its use, and acquiring software and hardware resources as needed.
- The DBA is accountable for problems such as security breaches and poor system response time. In large organizations, the DBA is assisted by a staff that carries out these functions.
- Database designers are responsible for identifying the data to be stored in the database and for choosing appropriate structures to represent and store this data.
- These tasks are mostly undertaken before the database is actually implemented and populated with data.
- It is the responsibility of database designers to communicate with all prospective database users in order to understand their requirements and to create a design that meets these requirements.
- In many cases, the designers are on the staff of the DBA and may be assigned other staff responsibilities after the database design is completed.
- Database designers typically interact with each potential group of users and develop views of the database that meet the data and processing requirements of these groups.
- Each view is then analyzed and integrated with the views of other user groups. The final database design must be capable of supporting the requirements of all user groups