In this section we discuss some of the advantages of using a DBMS and the capabilities that a good DBMS should possess. These capabilities are in addition to the four main characteristics discussed in Section. The DBA must utilize these capabilities to accomplish a variety of objectives related to the design, administration, and use of
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In addition to those who design, use, and administer a database, others are associated with the design, development, and operation of the DBMS software and system environment. These persons are typically not interested in the database content itself. We call them the workers behind the scene, and they include the following categories: DBMS system designers
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For a small personal database, such as the list of addresses discussed in Section, one person typically defines, constructs, and manipulates the database, and there is no sharing. However, in large organizations, many people are involved in the design, use, and maintenance of a large database with hundreds of users. In this section we identify
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A number of characteristics distinguish the database approach from the much older approach of programming with files. In traditional file processing, each user defines and implements the files needed for a specific software application as part of programming the application. For example, one user, the grade reporting office, may keep files on students and their
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Let us consider a simple example that most readers may be familiar with: a UNIVERSITY database for maintaining information concerning students, courses, and grades in a university environment. Figure shows the database structure and a few sample data for such a database. The database is organized as five files, each of which stores data records
An Example of Databases and Database Users Read More »
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
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Step 1 : The delivery valve is closed and the suction pipe, casing and portion of the delivery pipe up to the delivery valve are completely filled with the liquid so that no air pocket is left. This process is called priming a Centrifugal Pump. Step 2 : The electric motor is started to rotate
Working Principle of a Centrifugal Pump – Pedagogy Zone Read More »
Centrifugal pumps are the devices which convert the mechanical energy into hydraulic energy by means of centrifugal force acting on the fluid. Centrifugal pumps are classified as roto dynamic type of pumps in which a dynamic pressure is developed to lift liquids from lower level to higher level. The basic working principle of centrifugal pump
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In a double acting reciprocating pump, the suction and delivery strokes occur simultaneously. When the crank rotates from IDC to ODC, a vacuum is created on the left side of the piston and the liquid is sucked from the sump through suction valve S1. At the same time, the liquid on the right side of
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In a single acting reciprocating pumps, liquid acts on one side of the piston only. Image shows a single acting reciprocating pump which has one suction pipe and one delivery pipe. It is usually placed above the liquid level in the sump. When the crank rotates clockwise from dead centre (IDC) (from A) to outer
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