Database/DBMS Interview Questions And Answers

Database/DBMS Interview Questions And Answers - Part IX.

41) Define The Types Of Data Integrity Rules?

Answer: Data Integrity falls under the following three categories:

a) Entity Integrity: Entity integrity ensures that each row can be uniquely identified by an attribute
called the Primary key. The Primary key cannot have a NULL value.
b) Domain Integrity:Domain integrity refers to the range of valid entries for a given column. It ensures that there are only valid entries in the column.
c) Referential Integrity: Referential integrity ensures that for every value of a Foreign key, there is a
matching value of the Primary key. It states that "Foreign Key can be either a NULL value or should be Primary Key value of other relation".

42) What Is A Table? What Is A Tuple? What Is A Relation?

Answer: Table is a representation of a relation having records as rows and attributes as columns.

Tuple is nothing but a row in a table.

A relation consists of a homogeneous set of tuples. Informally a relation is a table.

Relations can be represented as two-dimensional data tables with rows and columns. The rows of a relation are called tuples. The columns of a relation are called attributes.
The attributes draw values from a domain (a legal pool of values). The number of tuples in a relation is called its cardinality while the number of attributes in a relation is called its degree.

A relation also consists of a schema and an instance. Schema defines the structure of a relation which consists of a fixed set of attribute domain pairs. An instance of a relation is a time-varying set of tuples where each tuple consists of attribute-value pairs.

43) What Are Extension & Intension?

Answer: Extension is the number of tuples (rows) present in a table at any instance. This is time dependent where as Intension is a constant value that gives the name, structure of table and the constraints laid on it.

A database is divided into schema and data. The schema describes the intentions (types) and the data describes the extension (data).

44) What Is A View? How It Is Related To Data Independence?

Answer: A view may be thought of as a virtual table, that is, a table that does not really exist in its own right but is instead derived from one or more underlying base table. In other words, there is no stored file that direct represents the view instead a definition of view is stored in data dictionary.

Growth and restructuring of base tables is not reflected in views. Thus the view can insulate users from the effects of restructuring and growth in the database. Hence accounts for logical data independence.

45) What Is A View? Discuss The Difference Between A View & A Base Relation?

Answer: View is the dynamic result of one or more relational operations operating on the base relations to produce another relation.

Base relation exists as a set of data in the database. A view does not contain any data, rather a view is defined as a query on one or more base relations and a query on the view is translated into a query on the associated base relations.

ALSO CHECK THE BELOW FAQ's:

46) What Is A Key? What Are Different Types Of Keys In A Database?
47) What Is A Primary Key & Secondary Key?
48) What Is A Candidate Key & Alternate Key?
49) What Is A Super Key & Composite Key?
50) What Is Foreign Key?

51) What Is Normalization. Explain It In Detail?
52) What Is The Need For Normalization In DBMS?
53) What Are The Goals Of Normalization In DBMS?
54) State The Benefits Of Normalization In DBMS?
55) What Is Functional Dependency?

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Tell Me Something About Yourself - Interview Answers.

Try to introduce some of your most important employment-oriented skills as well as your education and accomplishments to the interviewer. Answer to this question is very important because it positions you for the rest of the interview . That's why this statement is often called the "Positioning Statement". One should take the opportunity to show his/her communication skills by speaking clearly and concisely in an organized manner. Since there is no right or wrong answer for this question hence it is important to appear friendly. YOUR ANSWERS CAN BE: 1) I am a person with strong interpersonal skills and have the ability to get along well with people . I enjoy challenges and looking for creative solutions to problems. 2) Besides the details given in my resume, I believe in character values, vision and action. I am quick in learning from mistakes. I am confident that the various tests that you have conducted will corroborate my competencies apti...

What Is (Are) Your Weakness (Weaknesses)? - Interview Answers

There’s a saying – “However small the thorn maybe it has the ability to pierce.” Never say you are a Workaholic, a Perfectionist, etc. because it sounds negative. Try to convert these negative biased qualities into positive ones. For Example, In place of Workaholic you can say you are a hard worker and always willing to work for extra hours. In place of Perfectionist , you can say you are detail oriented and like to set high standard for work. “Try to specify your weakness as your strength and also highlight it as a benefit.” Your answers can be: 1) One of my weaknesses as I perceive is occasional compromise on time for quality and perfection. 2) I feel I am not very detail-oriented . I’m a person that wants accomplish as much as possible. I realized this hurts quality and therefore I‘m trying hard to find a balance between quality and quantity. 3) At times even when I need help, I try to solve my own problems instead of asking a co-worker who might know...

What Is (Are) Your Strengths? - Interview Answers

This is a simple and popular interview question. Generally people answer it in two ways. There are people who simply state their strength like “I am Young, Dynamic, Intelligent, Smart and so on…”. Such answer is neither right nor wrong but does not help u in any way also. Secondly there are peoples who state their strengths and explain them how he can use his strength for the job and industry. Do not simply state your strength. Everyone has some strength, all you need is to convert them into benefits. In short, try to advertise yourself by converting your features into strengths. “EVERYONE CLAIM THEY ARE HONEST, HARDWORKING, SMART AND SO ON….. BUT WITH AN EXAMPLE IT IS MUCH MORE BELIEVABLE.” Your answers can be : 1) I am a hard worker and because of this ability I can work for additional hours to accomplish my tasks.I am commitment oriented and hence I always enjoy the trust and confidence of my team mates which enables me to perform my duties very easily. 2) I am a...

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