Page 69 - DLIS405_INFORMATION_STORAGE_AND_RETRIEVAL

Information Storage and Retrieval Seema Sharma, Lovely Professional University

Notes
Unit 7: Sorting and Indexing

CONTENTS
Objectives

Introduction

7.1 Sorting
7.2 Online Catalogues

7.3 Online Research

7.4 Concept Indexing
7.5 Summary

7.6 Keywords
7.7 Review Questions

7.8 Further Readings

Objectives

After studying this unit, you will be able to:
• Define sorting
• Describe online catalogues and online research
• Explain concept indexing.

Introduction

Indexing and sorting are two approaches for establishing the order of data in a table. You use them
to answer different needs in an application. In general, you index a table to establish a specific order
of the rows, to help you locate and process information quickly. Indexing makes applications run
more efficiently. Use sorting only when you want to create another table with a different natural
order of rows.
Indexing orders rows in a specific sequence, usually in ascending or descending order on one field.
Indexing creates a list of rows arranged in a logical order, such as by date or by name, and stores
this list in a separate file called an index file. A dbase index (.MDX) file can have up to 47 indexes,
but only one controls the order of rows at any time. The index that is controlling the order is the
current master index.
Sorting an operation that segregates items into groups according to specified criterion.
A = {3 1 6 2 1 3 4 5 9 0}
A = {0 1 1 2 3 3 4 5 6 9}

64 LOVELY PROFESSIONAL UNIVERSITY