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Question:

Published on: 3 December, 2024

Write the difference between procedural and non-procedural query language.

Answer:

A query language is a language in which a user requests information from the database. These languages are usually on a level higher than that of a standard programming language. Query languages can be categorized as either procedural or non procedural.

In a procedural language, the user instructs the system to perform a sequence of operations on the database to compute the desired result. Ex.- PL/SQL

In a non procedural language, the user describes the desired information without giving a speciﬁc procedure for obtaining that information. Ex.- Relational Algebra, Relational Calculus.

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C Programming and Practices Computer Graphics and Multimedia Software Engineering Mobile computing Data Structures & Algorithm Design and Analysis of Algorithm

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3 December, 2024

Let T1, T2, T3 be transactions that operate on the same data items A, B, C. Let r1(A) means that T1 reads A, w1(A) means that T1 writes A and so on for T2 and T3. Consider the following schedule: S1: r2(C), r2(B), w2(B), r3(C), r1(A), w1(A), w3(B), w3(C), r2(A), r1(B), w1(B), w2(A). Is the schedule serializable and why?

3 December, 2024

What is the need for normalization? Explain 2nd and 3rd normal form with example.

Consider the following relation:

EMP_PROJ { SSn, Pnumber, Hours, Ename, Pname, Plocation}

Assume { SSn, Pnumber} as primary key.

The dependencies are {SSn, Pnumber}→ Hours; SSn →Ename; Pnumber → {Pname, Plocation}.

Normalize the above relation into 2NF.

23 January, 2022

Let R (ABCDE) be a relation schema and consider the following functional dependencies F = { AB→ E, AD→B, B→ C, C →D}. Find out the candidate key.