3i Infotech Papers: Sample Questions 685 - 686 of 1245

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Question number: 685

Essay Question▾

Describe in Detail

What is Relational Algebra?

Explanation

• The relational algebra is a theoretical procedural query language which takes instance of relations and does operations that work on one or more relations to describe another relation without altering the original relation.

• So, both the operands and the outputs are relations, and so the output from one operation can turn into the input to another operation which allows expressions to be nested in the relational algebra.

• The relational algebra is a relation-at-a-time (or set) language where all tuples are controlled in one statement without the use of loop.

• There are several variations of syntax for relational algebra commands and you use a common symbolic notation for the commands and present it informally.

• The primary operations of relational algebra are as follows:

• Select

• Project

• Union

• Set different

• Cartesian product

• Rename

Question number: 686

Essay Question▾

Describe in Detail

1. `main ()`
2. `{`
3. `    int i = 3;`
4. `    switch (i)`
5. `    {`
6. `        default: Printf ( “zero” );`
7. `        case 1: Printf ( “one” );`
8. `        break;`
9. `        case 2: Printf ( “two” );`
10. `        break;`
11. `        case 3: Printf ( “three” );`
12. `        break;`
13. `    }`
14. `}`

Explanation

In a program

 int i = 3 Integer variable i = 3 switch (i) { default: Printf (“zero”); case 1: Printf (“one”); break; case 2: Printf (“two”); break; case 3: Printf (“three”); break; } The switch corresponding case 3 (since i = 3) is selected And as there is a break statement after it. It comes out of the loop And answer is three