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Thursday, September 10, 2009

About Product,Companies and Databases

Hi friends,

Today I would like to present few points related to Product,Companies and Databases which would be helpful for the readers.

Round:About Product and Companies

1.How is the company that tells the “System applications and products for data processing”better known as?

2.Five colleagues working for patni computers ,resigned their job and started a company with an investment of 10000.Today this company is a house hold name. Which company we are talking about?

3.Mark Shuttleworth is a South African entrepreneur who was the second self funded space tourist. Which software product is he responsible for?


4.Which product is advertised “Hello coming in june”.This product is now a rage and set the benchmark in its category.

5.Microsoft is accused by Apple to have copies of Apple's windows or gui concept. From which company/organization did Apple copy it from?


1.What is surrogate key?
A surrogate key in a is a unique identifier for either an entity in the modeled world or an object in the database. The surrogate key is not derived from application data.
A surrogate should have the following
the value is unique system-wide, hence never reused;
the value is system generated;
the value is not manipulable by the user or application;
the value contains no semantic meaning;
the value is not visible to the user or application;

2.What is the difference between union and unionall?
Union will filter duplicate values but union all will not filter duplicate values.

3.Every non-key attribute if fully functionally dependent on primary key.Which normal form it is?
2nd Normal form.

4.What is the difference between primary key and unique key?
The column holding the primary key constraint cannot accept null values.whereas column holding the unique constraint can accept null values .

5.What is the difference between DELETE TABLE and TRUNCATE TABLE?
TRUNCATE is a DDL command and cannot be rolled back. All of the memory space is released back to the server.
DELETE is a DML command and can be rolled back.

Hope this topic was useful to you, Please Post your comments!

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