1. LIS 384K.11 Database-Management Principles and Applications
Introduction
R. E. Wyllys
Copyright © 2002 by R. E. Wyllys
Last revised 2002 Jan 28
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

2. Course Objectives: To Develop an
Understanding of the nature of database-management systems (DBMSs), including their structure, design, and evaluation
Understanding of the relationship between DBMSs and the analysis of information systems in libraries and in business
Understanding of the distinctions among flat-file databases (DBs), network DBs, hierarchical DBs, relational DBs, and text-oriented DBs
Understanding of the process of normalization of relational DBs
Understanding of the role of the Structured Query Language (SQL) standards in the current and future development of DBMSs
Understanding of management and social issues such as database security and privacy
Introductory level of skill in the use of a microcomputer database-management system (Microsoft Access)
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

3. Examples of Databases What does the word "database" mean?
Nowadays we usually think it means a computer-stored set of information
However, databases can exist in many forms. Examples:
Electronic data: text, visual images, audio images, numbers
Sheets of paper in folders in a vertical file
A book (think of it as a collection of sentences and illustrations)
Books in a collection (e.g., a library)
Sets of 3"x5" cards containing notes
Blueprints
Maps
Core samples from oil wells
Blood samples in a medical laboratory
DNA samples in a forensic laboratory
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LIS 384K.11, Database-Management Principles and Applications

4. Examples of Databases What do these examples have in common?
Sets of data and information composed of, and/or represented by: bits; or alphanumeric symbols; or lines and shapes in drawings, pictures, and maps; or audio recordings; or video recordings; or realia (i.e., actual substances)
At least one means by which the sets of data and information are organized in order to facilitate access to individual desired sets
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

5. Examples of Databases
Consider the provisions for access to individual pieces of information in the following examples:
Phone book. Contains a collection of several independent (discrete) databases, each consisting of names together with corresponding phone numbers:
White-pages personal listings, arranged alphabetically by surname and within surname by first names
White-pages corporate listings, arranged alphabetically
Blue-pages governmental listings: primary arrangement alphabetical by type of government (city, county, state, federal), secondary arrangement alphabetical by agency within type of government, tertiary arrangement alphabetical by office within agency
Yellow-pages listings: primary arrangement by type of business, secondary arrangement alphabetically by company within type of business, plus various special groupings (e.g., restaurants by ethnic type)
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

6. Examples of Databases
Provisions for access to individual pieces of information, cont'd:
Organizational membership directory, usually consisting of names together with corresponding postal addresses, telephone numbers, and addresses
Typically contains listings by surname and first names, plus groupings by regions (e.g., states, countries) and by membership in special interest groups (SIGs), arranged alphabetically by name within regional groups and SIGs
Dictionary, consisting of words with corresponding definitions, and in some cases, lists of synonyms and/or antonyms
Primary collection is individual words arranged alphabetically
May contain separate sections (e.g., geographical names, biographical names, abbreviations, proofreaders' marks)
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

7. Examples of Databases
Provisions for access to individual pieces of information, cont'd:
Thesaurus
Primary arrangement by broad concepts (themes), with subgroupings of sets of closely related words (often arranged by type of speech, e.g., nouns, verbs), each set sharing a subconcept of the primary concept; sometimes includes antonyms of the primary concept and/or selected subconcepts
Book (non-fiction)
Table of contents
Provides access to chapters (and sometimes to subchapters) dealing with broad topics that are aspects of the overall subject(s) of the book
Index
Organizes narrow concepts by names, terms, subterms, etc.
Provides pointers from terms to relevant locations in text of book
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

8. Examples of Databases
The foregoing examples illustrate some ways of organizing information in DBs, whether computerized or non-computerized: viz.,
An intrinsic index provides information organized by and with the entry or record (e.g., a Rolodex card); or
A separate index can point to the location of the information (e.g., a book index, or a library catalog); or
Records (i.e., basic packages of information) can contain retrieval tags (access tags, labels, etc.) that identify them and that can be searched for (e.g., labelled folders in a file); or
(Worst Case) Records can be sought via exhaustive search (by humans or computer programs)
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

9. Computerized Databases
Consist of
Bits, organized into bytes, which in turn are organized into sequences or strings of bytes
Fields: sets of bytes that represent information
Records: sets of fields that are associated by sharing relevance to some entity
Files: sets of records sharing relevance to a particular type of entity
Databases typically consist of one or more sets of related files
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LIS 384K.11, Database-Management Principles and Applications

10. Computerized Databases
Of special interest are Relational Databases (RDBs) and programs that manage them, known as Relational Database Management Systems (RDBMSs).
Note: The word "relational" is often omitted nowadays, since most well known DBMSs (e.g., IBM DB2, Informix, MS Access, MS SQL Server, Oracle, Sybase) are RDBMSs.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

11. Introduction to RDBs
In discussing relational databases, we use synonymously the words
File, table, relation
Record and row
Field, column, attribute
Note: Discussions of RDB theory tend to prefer the words italicized above
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LIS 384K.11, Database-Management Principles and Applications

12. Introduction to RDBs Definition:
A relational database is a set of one or more tables that together embody information about a set of related concepts and entities.
If (as is usually the case) a relational database has more than one table, the tables are connected (related) in the following way:
It is possible to move from any one table in the RDB to any other table in the RDB via a chain of columns (i.e., fields, attributes) shared in pairwise fashion by successive tables.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

13. Introduction to RDBs
The picture below shows 3 tables, with a total of 12 attributes (i.e., 12 distinct columns). The top and middle tables share Attribute 3; the middle and bottom tables share Attribute 7.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

14. Introduction to RDBs Definition:
A database application is a combination of
A relational database-management system (RDBMS)
A relational database (RDB)
Associated menus, data-entry forms, and report forms
Documentation (e.g., manuals) for the users.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

15. Introduction to RDBs
An application is a package designed to facilitate a particular real-world function (or a set of related functions): e.g., looking up books in a library catalog, or handling a sales transaction in a store.
Note: An application may include more than one RDB, and/or it may include a "stray" table or two, so long as such additions serve the basic function and make the whole package more convenient for humans to use.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

16. Various Types of DBs Types of Databases Flat file (spreadsheet)
Hierarchical
Network
Relational
Text-oriented
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LIS 384K.11, Database-Management Principles and Applications

17. Flat File DBs
Flat file DBs are like the DBs you can construct in a spreadsheet, i.e., all the information in the DB is in one file consisting of one array of rows and columns.
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LIS 384K.11, Database-Management Principles and Applications

18. Flat File DBs Flat file databases (spreadsheet style) Advantages
Simple
Suitable for small numbers of records with few attributes
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LIS 384K.11, Database-Management Principles and Applications

19. Flat File DBs Flat file databases (spreadsheet style) Disadvantages
Likely to include repetitions of data
Multi-valued attributes (e.g., multiple authors, multiple phone numbers) require repetitions of accompanying data
Changes in data are difficult to implement
Deletion and insertion anomalies are common
Often lead to too much information in one table
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LIS 384K.11, Database-Management Principles and Applications

20. Hierarchical DBs GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

21. Hierarchical DBs Hierarchical databases
Based on a classification scheme (a taxonomy)
First databases were designed for banking. Hierarchical databases were appropriate for such purpose
Typically require custom programming
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

22. Network DBs GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

23. Network DBs Network databases
Can be extremely complex and difficult to manage
World-Wide Web is a very large example of a network database
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

24. Text-Oriented DBs
Text-oriented DBs are, as their name suggests, DBs that have special features for handling text: e.g., abilities
To search for specified strings of characters
With or without matching the cases of the characters
While using wildcards, i.e., symbols that will match any one character or any sequence of characters
With or without automatic inclusion of word variants, e.g., plurals, "ing" verb endings
To search on pairs, triples, etc., of words and phrases, using
Boolean logic
Proximity logic (e.g. both words must be in same sentence, or in same paragraph, or in same section, or within n words of each other)
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LIS 384K.11, Database-Management Principles and Applications

25. Text-Oriented DBs Examples of abilities of text-oriented DBs, cont'd
To rank search results by weights assigned to the terms used in the search
To maintain thesauri of near synonyms and to allow searches by near synonyms of original query terms
To maintain, for selected words or phrases, indexes of their locations in files
Commercial text-oriented DBs exist (e.g., Lexis-Nexis and Dialog), running on large computer systems.
The only text-oriented DBMSs for microcomputers that I know of are askSam, DB/Textworks, Isys, and STAR.
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

26. Advantages of RDBs Advantages of relational databases
Cut down on needless repetition of information
Ensure more accuracy
Facilitate updating and deletion of information.
Design avoids problems that occur with flat files, e.g., insertion and deletion anomalies
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

27. Relational Databases
In a RDB, the information content of a table does not depend on either
The order of the rows; or
The order of the columns
In other words, the rows and columns of a table can be rearranged at will without affecting the table's information content
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications

28. Relational Databases In a RDB, each table A primary key is
Must have a primary key (unique identifier)
Must have no duplicate rows
A primary key is
A data attribute (column), or a combination of attributes, that uniquely identifies each record in the table.
A simple key consists of a single attribute
A composite key consists of two or more attributes
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LIS 384K.11, Database-Management Principles and Applications

29. Relational Databases Primary Key
Provides unique way to identify each record
Can be obvious from the structure of the table. If there is no easy natural choice, you can add a column containing a unique identifier.
May consist of the entire record (especially with two-column tables, which occur often in the development of RDBs)
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LIS 384K.11, Database-Management Principles and Applications

30. Computerized Databases--
They can help to save you from this kind of work!
GSLIS - The University of Texas at Austin
LIS 384K.11, Database-Management Principles and Applications