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What is magnetic disks?explain it?
Magnetic disk provides the bulk of secondary storage of modern computer system. The disk capacity is growing at over 50% per year. But the storage needs of large applications have also been growing very fast and in some case each faster than the growth rate of disk capacities. A large data base may need 100 of disks.
Physical characteristics of disk
Physical disks are relatively simple. Every disc platter has a flat circular shape
We can call magnetic disk as
Ø hard disk
Ø Floppy disk
The read write head keeps information on a sector magnetically as reversals of the direction of magnetization of the magnetic material. There might be hundreds of concentric tracks on a disc surface, having thousands of sectors.
Explain the Cartesian product: The Cartesian product operation does not need relations to union-compatible. The meaning of this is that the involved relations may have dissim
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Analyzing Association Traversal Association Traversal shall be understood properly for the association design explanation. Analyzing association traversal means analyzing tra
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What is an E-R model? Draw an E-R Diagram for the company database with following Descriptions? The company is organized within departments. Each department has a unique name a
What are referential integrity constraints? A value that appears in single relation for a given set of attributes also appears for a particular set of attributes in another rel
Explain the steps for reduction of E-R model into relational model. Ans:(a) Entity set in E-R model will be considered as table name in relational Model. (b) Attributes of e
These permit the user to unload a database or parts of a database and reload the data on the similar machine, or on another machine in a dissimilar location. This can be useful in
What is Derived and stored Attribute? Derived and Stored Attribute - In a few cases, two or more attribute values are associated, for example, Age and BirthDate attributes of a
what is the need of a log in dbms
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