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Relational Database Interview Questions & Answers - Learning Mode
COOLINTERVIEW.COM DATABASE INTERVIEW QUESTIONS RELATIONAL DATABASE INTERVIEW QUESTIONS QUESTIONS & ANSWERS - LEARNING MODE

Relational Database Interview Questions & Answers - Learning Mode

A relational database is a digital database whose organization is based on the relational model of data, as proposed by E. F. Codd in 1970. The various software systems used to maintain relational databases are known as a relational database management system (RDBMS). A relational database is a collection of data items organized as a set of formally-described tables from which data can be accessed or reassembled in many different ways without having to reorganize the database tables.

Try Relational Database Interview Questions & Answers - Exam Mode

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Relational Database Interview Questions & Answers - Learning Mode
Try Relational Database Interview Questions & Answers - Exam Mode
Question: What is Fully Functional dependency?

Answer: It is based on concept of full functional dependency. A functional dependency X --> Y is full functional dependency if removal of any attribute A from X means that the dependency does not hold any more. Source: CoolInterview.com
Question: A B C is a set of attributes. The functional dependency is as follows
AB -> B
AC -> C
C -> B?


Answer: a) is in 1NF
b) is in 2NF
c) is in 3NF
d) is in BCNF

(a) is in 1NF since (AC)+ = { A, B, C} hence AC is the primary key. Since C B is a FD given, where neither C is a Key nor B is a prime attribute, this it is not in 3NF. Further B is not functionally dependent on key AC thus it is not in 2NF. Thus the given FDs is in 1NF.
Source: CoolInterview.com
Question: What are stand-alone procedures?

Answer: Procedures that are not part of a package are known as stand-alone because they independently defined. A good example of a stand-alone procedure is one written in a SQL*Forms application. These types of procedures are not available for reference from other Oracle tools. Another limitation of stand-alone procedures is that they are compiled at run time, which slows execution. Source: CoolInterview.com
Question: When is a functional dependency F said to be minimal?

Answer: ► Every dependency in F has a single attribute for its right hand side.
► It cannot replace any dependency X -->A in F with a dependency Y--> A where Y is a proper subset of X and still have a set of dependency that is equivalent to F.
► We cannot remove any dependency from F and still have set of dependency that is equivalent to F. Source: CoolInterview.com
Question: What is meant by Proactive, Retroactive and Simultaneous Update?

Answer: Proactive Update:
The updates that are applied to database before it becomes effective in real world .
Retroactive Update:
The updates that are applied to database after it becomes effective in real world .
Simulatneous Update:
The updates that are applied to database at the same time when it becomes effective in real world . Source: CoolInterview.com
Question: What are Armstrong rules? How do we say that they are complete and/or sound?

Answer: The well-known inference rules for FDs
? Reflexive rule :
If Y is subset or equal to X then X Y.
► Augmentation rule:
If X Y then XZ YZ.
► Transitive rule:
If {X Y, Y Z} then X Z.
► Decomposition rule :
If X YZ then X Y.
► Union or Additive rule:
If {X Y, X Z} then X YZ.
► Pseudo Transitive rule :
If {X Y, WY Z} then WX Z.
Of these the first three are known as Amstrong Rules. They are sound because it is enough if a set of FDs Source: CoolInterview.com
Question: What is SDL (Storage Definition Language)?

Answer: This language is to specify the internal schema. This language may specify the mapping between two schemas
Source: CoolInterview.com
Question: Spurious tuples may occur due to?

Answer: i. Bad normalization
ii. Theta joins
iii. Updating tables from join
a) i & ii b) ii & iii
c) i & iii d) ii & iii

(a) i & iii because theta joins are joins made on keys that are not primary keys. Source: CoolInterview.com
Question: What is 4NF?

Answer: A relation schema R is said to be in 4NF if for every Multivalued dependency X --> Y that holds over R, one of following is true
► X is subset or equal to (or) XY = R.
► X is a super key.
Source: CoolInterview.com
Question: What is 5NF?

Answer: A Relation schema R is said to be 5NF if for every join dependency {R1, R2, ..., Rn} that holds R, one the following is true

► Ri = R for some i.
► The join dependency is implied by the set of FD, over R in which the left side is key of R.
Source: CoolInterview.com
Question: What is Relational Algebra?

Answer: It is procedural query language. It consists of a set of operations that take one or two relations as input and produce a new relation. Source: CoolInterview.com
Question: What is Storage Manager?

Answer: It is a program module that provides the interface between the low-level data stored in database, application programs and queries submitted to the system.
Source: CoolInterview.com
Question: What is VDL (View Definition Language)?

Answer: It specifies user views and their mappings to the conceptual schema. Source: CoolInterview.com
Question: What is Set-at-a-time or Set-oriented?

Answer: The High level or Non-procedural DML can specify and retrieve many records in a single DML statement. This retrieve of a record is said to be Set-at-a-time or Set-oriented. Source: CoolInterview.com
Question: How does Tuple-oriented relational calculus differ from domain-oriented relational calculus?

Answer: The tuple-oriented calculus uses a tuple variables i.e., variable whose only permitted values are tuples of that relation. E.g. QUEL

The domain-oriented calculus has domain variables i.e., variables that range over the underlying domains instead of over relation. E.g. ILL, DEDUCE. Source: CoolInterview.com
Question: What is DML (Data Manipulation Language)?

Answer: This language that enable user to access or manipulate data as organised by appropriate data model.

► Procedural DML or Low level: DML requires a user to specify what data are needed and how to get those data.
► Non-Procedural DML or High level: DML requires a user to specify what data are needed without specifying how to get those data.
Source: CoolInterview.com
Question: What is Record-at-a-time?

Answer: The Low level or Procedural DML can specify and retrieve each record from a set of records. This retrieve of a record is said to be Record-at-a-time. Source: CoolInterview.com
Question: What is Authorization and Integrity manager?

Answer: It is the program module, which tests for the satisfaction of integrity constraint and checks the authority of user to access data.
Source: CoolInterview.com
Question: What is DML Compiler?

Answer: It translates DML statements in a query language into low-level instruction that the query evaluation engine can understand. Source: CoolInterview.com
Question: What is DDL Interpreter?

Answer: It interprets DDL statements and record them in tables containing metadata. Source: CoolInterview.com

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