# 3i Infotech Placement: Sample Questions 261 - 262 of 1245

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## Question 261

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### Statement

True-False▾

Constraints cannot be exported through Export command.

FALSE

### Explanation

• Export command can export constraints- it can specify whether table constraints should be exported with table data.
• For import in the normal import order- referential constrains are imported only after all tables are imported.
• This sequence prevents errors that occur when constraints can fail when data has not been fully imported.
• When an error occurs, import generates an error message for failed row and continues importing other rows in the table.
• Constrain export can be disabled to avoid this.

## Question 262

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### Describe in Detail

Essay▾

Define of common data structures:

Stack

Queue

General purpose of linked list

Singly vs. doubly linked lists.

### Explanation

• Stack:
• Stack is a linear data structure which follows a particular order in which the operations are performed.
• The order LIFO (Last In First Out) or FILO (First In Last Out) .
• Queue:
• Linear data structure.
• Additions are made at the end or tail of the queue while removals are made from the front or head of the queue.
• Queue is referred to FIFO structure for its First in First Out Access.
• General purpose of linked list
• A linear data structure
• Common data structure consisting of group of nodes in a sequence divided in two parts.
• Each node consists of its own data and the address of the next node and forms a chain.
• Used to create trees and graphs.
• Singly vs. doubly linked lists.
 Singly Linked List Doubly Linked List Allow one way travel- can access successor Allows two way travel using two pointers next and previous Uses less memory per node Uses more memory per node than singly linked list Complexity of insertion and deletion at known position is O (n) Complexity of Insertion and Deletion at known position is O (1) . There is a allowing delete from a singly-linked list in O (1) , but the list must be circular Used in places where singly-linked lists would not work but they require slightly more “housekeeping” , and are slightly less efficient on insertions as the result Each node contains at least two parts:Infolink Each node contains at least three parts:InfoLink to next nodeLink to previous node.

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