Introduction To Database Questions and Answers

Q: The conceptual model is

Correct answer: Independent of both hardware and softwareThe conceptual model describes what data the organisation needs and how it is related, in terms of the business rather than of any machine or product. That independence is what lets the same model survive a change of hardware or a move to a different DBMS.

Q: __________________ is collection of interrelated data and set of program to access them.

Correct answer: Database Management SystemA DBMS is defined as a collection of interrelated data together with a set of programs to access it. The data alone is the database; adding the software that creates, queries and administers it gives the database management system.

Q: Which of the following database objects does not physically exist?

Correct answer: ViewA view is a stored query: it has no data of its own, and its rows are computed whenever it is referenced. Base tables and indexes both occupy real storage. (A materialised view is the exception that proves the rule - it is stored precisely because an ordinary view is not.)

Q: A subschema expresses

Correct answer: The external view.A subschema is the external view: what one particular application or user group sees. The logical view is the whole database as a single community picture, and the physical view is how it is actually stored.

Q: Which of the following products was the first to implement true relational algebra in a PC DBMS?

Correct answer: R:baseR:base was the first PC product to implement true relational algebra. dBase-II, though far more widely used, was a file-oriented product without genuine relational operations - a distinction that mattered a great deal in the arguments of the mid-1980s.

Q: A file manipulation command that extracts some of the records from a file is called

Correct answer: SELECTSelect extracts rows that satisfy a condition - the horizontal slice. Project takes columns, join combines two relations on matching values, and product pairs every row with every row. (Confusingly, SQL’s SELECT statement performs projection as well; the relational operator named select is what the WHERE clause does.)

Q: A table joined with itself is called

Correct answer: Self JoinA self join joins a table to itself, using two different aliases so that the two copies can be distinguished. It is how a table that refers to its own rows is unravelled - listing each employee beside their manager, where both are rows of the same employee table.

Q: Which of the following products was an early implementation of the relational model developed by E.F. Codd of IBM?

Correct answer: DB2DB2 was IBM’s commercial relational product, descended from the System R research prototype built to test E. F. Codd’s 1970 relational model. IDMS implemented the older CODASYL network model, and dBase-II and R:base were PC products of the 1980s.

Q: A data dictionary is a special file that contains:

Correct answer: All of the aboveA data dictionary holds the complete description of the data: the name, type and width of every field in every file, together with keys, indexes, constraints and often who may access what. It is metadata, and in a relational database it is itself queryable.

41.

The relational model feature is that there

A.Is no need for primary key data
B.Is much more data independence than some other database models
C.Are explicit relationships among records
D.Are tables with many dimensions

Answer: B

Correct answer: Is much more data independence than some other database models

The relational model’s advantage is data independence: relationships are expressed by matching values in key columns, not by stored pointers, so tables can be reorganised or indexed differently without touching the applications. The older hierarchical and network models embedded the access path in the structure itself, which is what made them rigid.

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42.

The conceptual model is

A.Dependent on hardware
B.Dependent on software.
C.Dependent on both hardware and software
D.Independent of both hardware and software

Answer: D

Correct answer: Independent of both hardware and software

The conceptual model describes what data the organisation needs and how it is related, in terms of the business rather than of any machine or product. That independence is what lets the same model survive a change of hardware or a move to a different DBMS.

Discuss in Forum

43.

__________________ is collection of interrelated data and set of program to access them.

A.Data Structure
B.Programming language
C.Database Management System
D.Database

Answer: C

Correct answer: Database Management System

A DBMS is defined as a collection of interrelated data together with a set of programs to access it. The data alone is the database; adding the software that creates, queries and administers it gives the database management system.

Discuss in Forum

44.

Which of the following database objects does not physically exist?

A.Base table
B.Index
C.View
D.None of the above

Answer: C

Correct answer: View

A view is a stored query: it has no data of its own, and its rows are computed whenever it is referenced. Base tables and indexes both occupy real storage. (A materialised view is the exception that proves the rule - it is stored precisely because an ordinary view is not.)

Discuss in Forum

45.

A subschema expresses

A.The logical view
B.The physical view.
C.The external view.
D.All of the above.

Answer: C

Correct answer: The external view.

A subschema is the external view: what one particular application or user group sees. The logical view is the whole database as a single community picture, and the physical view is how it is actually stored.

Discuss in Forum

46.

Which of the following products was the first to implement true relational algebra in a PC DBMS?

A.IDMS
B.Oracle
C.dBase-II
D.R:base

Answer: D

Correct answer: R:base

R:base was the first PC product to implement true relational algebra. dBase-II, though far more widely used, was a file-oriented product without genuine relational operations - a distinction that mattered a great deal in the arguments of the mid-1980s.

Discuss in Forum

47.

A file manipulation command that extracts some of the records from a file is called

A.SELECT
B.PROJECT
C.JOIN
D.PRODUCT

Answer: A

Correct answer: SELECT

Select extracts rows that satisfy a condition - the horizontal slice. Project takes columns, join combines two relations on matching values, and product pairs every row with every row. (Confusingly, SQL’s SELECT statement performs projection as well; the relational operator named select is what the WHERE clause does.)

Discuss in Forum

48.

A table joined with itself is called

A.Join
B.Self Join
C.Outer Join
D.Equi Join

Answer: B

Correct answer: Self Join

A self join joins a table to itself, using two different aliases so that the two copies can be distinguished. It is how a table that refers to its own rows is unravelled - listing each employee beside their manager, where both are rows of the same employee table.

Discuss in Forum

49.

Which of the following products was an early implementation of the relational model developed by E.F. Codd of IBM?

A.IDMS
B.DB2
C.dBase-II
D.R:base

Answer: B

Correct answer: DB2

DB2 was IBM’s commercial relational product, descended from the System R research prototype built to test E. F. Codd’s 1970 relational model. IDMS implemented the older CODASYL network model, and dBase-II and R:base were PC products of the 1980s.

Discuss in Forum

50.

A data dictionary is a special file that contains:

A.The name of all fields in all files.
B.The width of all fields in all files.
C.The data type of all fields in all file
D.All of the above

Answer: D

Correct answer: All of the above

A data dictionary holds the complete description of the data: the name, type and width of every field in every file, together with keys, indexes, constraints and often who may access what. It is metadata, and in a relational database it is itself queryable.

Discuss in Forum

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