Database Users and Administrators




A primary goal of a database system is to retrieve information from and store
new information into the database. People who work with a database can be
categorized as database users or database administrators.


1. Database Users and User Interfaces


There are four different types of database-system users, differentiated by the way
they expect to interact with the system. Different types of user interfaces have
been designed for the different types of users.


Na¨?ve users are unsophisticated users who interact with the system by invoking
one of the application programs that have been written previously.
For example, a clerk in the university who needs to add a new instructor to
department A invokes a program called new hire. This program asks the clerk
for the name of the new instructor, her new ID, the name of the department
(that is, A), and the salary.

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    The typical user interface for na¨?ve users is a forms interface, where the
user can fill in appropriate fields of the form. Na¨?ve users may also simply
read reports generated from the database.

     As another example, consider a student, who during class registration
period, wishes to register for a class by using a Web interface. Such a user
connects to a Web application program that runs at a Web server. The application
first verifies the identity of the user, and allows her to access a form
where she enters the desired information. The form information is sent back
to the Web application at the server, which then determines if there is room
in the class (by retrieving information from the database) and if so adds the
student information to the class roster in the database.


Application programmers are computer professionalswho write application
programs. Application programmers can choose frommany tools to develop
user interfaces. Rapid application development (RAD) tools are tools that enable
an application programmer to construct forms and reportswith minimal
programming effort.


Sophisticated users interact with the system without writing programs. Instead,
they form their requests either using a database query language or by
using tools such as data analysis software. Analysts who submit queries to
explore data in the database fall in this category.

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Specialized users are sophisticated users who write specialized database
applications that do not fit into the traditional data-processing framework.
Among these applications are computer-aided design systems, knowledgebase
and expert systems, systems that store data with complex data types (for
example, graphics data and audio data), and environment-modeling systems.

2.  Database Administrator


One of the main reasons for using DBMSs is tohave central control of both thedata
and the programs that access those data. A person who has such central control
over the system is called a database administrator (DBA). The functions of a DBA
include:


• Schema definition. The DBA creates the original database schema by executing
a set of data definition statements in the DDL.


• Storage structure and access-method definition.

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• Schema and physical-organization modification. TheDBAcarries out changes
to the schema and physical organization to reflect the changing needs of the
organization, or to alter the physical organization to improve performance.

• Granting of authorization for data access. By granting different types of
authorization, the database administrator can regulate which parts of the
database various users can access. The authorization information is kept in a
special system structure that the database system consults whenever someone
attempts to access the data in the system.


• Routine maintenance. Examples of the database administrator’s routine
maintenance activities are:


? Periodically backing up the database, either onto tapes or onto remote
servers, to prevent loss of data in case of disasters such as flooding.


? Ensuring that enough free disk space is available for normal operations,
and upgrading disk space as required.

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? Monitoring jobs running on the database and ensuring that performance
is not degraded by very expensive tasks submitted by some users.



Frequently Asked Questions

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Ans: Researchers have developed several data-models to deal with these application domains, including object-based data models and semi-structured data models. view more..
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Ans: The term data mining refers loosely to the process of semi-automatically analysing large databases to find useful patterns. view more..
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Ans: The architecture of a database system is greatly influenced by the underlying computer system on which the database system runs. Database systems can be centralized, or client-server, where one server machine executes work on behalf of multiple client machines. view more..
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Ans: A primary goal of a database system is to retrieve information from and store new information into the database. People who work with a database can be categorized as database users or database administrators. view more..
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Ans: Information processing drives the growth of computers, as it has from the earliest days of commercial computers. In fact, automation of data processing tasks predates computers. view more..
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Ans: A relational database consists of a collection of tables, each of which is assigned a unique name. view more..
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Ans: The database schema is the logical design of the database. view more..
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Ans: A super-key is a set of one or more attributes that, taken collectively, allow us to identify uniquely a tuple in the relation. view more..
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Ans: DBMS typically includes a database security and authorization subsystem that is responsible for ensuring the security of portions of a database against unauthorized access view more..
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Ans: The typical method of enforcing discretionary access control in a database system is based on the granting and revoking of privileges. Let us consider privileges in the context of a relational DBMS. view more..
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Ans: This chapter discusses techniques for securing databases against a variety of threats. It also presents schemes of providing access privileges to authorized users. view more..
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Ans: This chapter discusses techniques for securing databases against a variety of threats. It also presents schemes of providing access privileges to authorized users. view more..
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Ans: Object databases is the power they give the designer to specify both the structure of complex objects and the operations that can be applied to these objects view more..
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Ans: XML (Extensible Markup Language)—has emerged as the standard for structuring and exchanging data over the Web. XML can be used to provide information about the structure and meaning of the data in the Web pages rather than just specifying how the Web pages are formatted for display on the screen view more..
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Ans: A database schema, along with primary key and foreign key dependencies, can be depicted by schema diagrams. view more..
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Ans: A query language is a language in which a user requests information from the database. view more..
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Ans: All procedural relational query languages provide a set of operations that can be applied to either a single relation or a pair of relations. view more..
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Ans: An object database is a database management system in which information is represented in the form of objects as used in object-oriented programming. Object databases are different from relational databases which are table-oriented. Object-relational databases are a hybrid of both approaches. view more..




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