1. Database Introduction
History
Why we want to use them
Other fun
Copyright © by Curt Hill

2. Six Generations of Data Management
Manual – Prehistory
Punch cards – 1900
Programmed Unit record – 1955
Online database – 1965
Client Server, Relational – 1980
Multimedia – 1995
All of these still continue
Data Management: Past, Present, and Future, by Jim Gray
Microsoft Research, Technical Report MSR–TR–96-18
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Manual
Writing has existed for millennia
Kings used writing to inventory their goods, record their laws
Sumerian tablets date from 2000 BC or before
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Punch cards
Originally used by Jacquard to program silk weaving machines
Not really data management
Hollerith used to record census data in 1890
A suite of machines that would punch, sort, print and tabulate from cards
Programmed by rewiring control panels
Known as unit record or electronic accounting machines
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Machines
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6. Programmed Unit record
Stored program computers change the face of data management
Tapes store the data much more densely than cards
Programming removes the limits on what sort of calculations or transformations may be done on the data
Produced a file-oriented record processing approach
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Consider an example
A college has many files that describe their system
Faculty
Catalog or courses
Grades
Students
Among many others
We will look at payroll and grades as an example
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Payroll File Fields
Name
Address
Salary/wage
Earnings Year to Date
Among very many more
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Payroll File
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Grades Fields
Course
Including section
Student name
Term
Letter grade
Instructor
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Grades File
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12. Background Vocabulary
fields
collection of related characters
records
collection of related fields
files
collection of related records
database
collection of related files
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How to use
Actions we might want on each file:
Create
Update (add, remove, change records)
Sort
Generate any of several reports
Each action for each file would be a program for an overworked programming staff
Typically a COBOL program
Eight programs, or sections of programs, for two files
These are typically done in a batch environment
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First Database?
Integrated Data Store (IDS) appears to be the first DBMS
Architect is Charles Bachman
1973 Turing award winner
First ran in 1963 on GE hardware
It was a network database
Not originally online, since there was no Internet
Later connected to Teletypes for updating inventory
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IDS Capabilities
Single interface between application programs and the data
Maintained metadata on the data
Data independence
Schemas can be changed without changing applications
Implemented a buffer manager
Restricted form of ACID
Later implemented a backup and recovery system
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Online database
Many things do not work well in batch mode:
Travel reservations need up to the second information
The database is born
Started out as disk based unit record, but that is not the best organization for this type of application
Developed into two models:
Hierarchical and network
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Two Models
Both require direct access devices
Each requires disk addresses in the database
Required to get to the pointed at record directly
Programmer as navigator
Access programs must still be written specially for a particular database
Must understand the low level structure
Must run on the same machine as database
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18. Client Server, Relational
EF Codd suggests the relational model and he and other develop a substantial theoretical base
Queries may now be simple and short
Needs to know a schema, but not complete organization
This allows transmission of a simple query
Client server computing is born
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19. Relational Database The key The solution
All the programs previously described are about the same – every update is nearly the same
All that changes is the underlying file
The solution
Describe the file in a general way
Generate a program that handles the file based on the description
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20. How to describe a file A file is a collection of records
Each record is a collection of fields
Typically only one type of record in a file
Each field is described by a:
Name
Type
For example numeric, string, boolean etc.
Length
Booleans have a predefined length, others require specification
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SQL
Structured Query Language
Has become the “standard” for queries
A relational database does not have to accept SQL
Unless it wants to be commercially viable
SQL is mostly declarative but with some procedural features
Declarative – what is wanted
Procedural – how to get it
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The Files
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23. What is wrong with the original example?
Redundancy in faculty description
Space is wasted
Discrepancies may occur between grades and payroll
Some reports need to access multiple files
Eg. Transcript generation
Complicates the programming issue
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24. Advantages (1 of 3) Data independence Efficient access
Application program no longer need some or all of the files
Do not know or care how data is stored, aka abstraction
Simplifies application development
Efficient access
The DBMS employs sophisticated access techniques seldom used by normal programmers
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25. Advantages (2 of 3) Integrity constraints Security
The DBMS may check data in a way seldom done in normal file processing
Eg. Account validity
Security
A DBMS may enforce requirements on who can access the data and in what way
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26. Advantages (3 of 3) Administration Concurrent access
Minimize redundancy
Manage sharing of the data
Optimize for the enterprise, not a small group
Easier to backup the data
Concurrent access
Manages the simultaneous update problem
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27. Disadvantages A DBMS is:
Complex
Expensive
Bulky
Simple file access is much quicker and less expensive
The view a DBMS provides may not be helpful to a particular application
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Multimedia
The relational model was king for a time
What if what we to store does not conform to the notion of typed text?
Sound, pictures, video
One of the results is the object oriented data base which stores data as objects
Data and programs to manipulate
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NoSQL
Once it is realized that the relational database is not the end-all, all manner of new types of databases appear
These are the NoSQL databases
SQL is the universal query language
NoSQL may mean no SQL or Not Only SQL
This is a field that is not finished developing
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Finally
The course focuses on relational data bases
They are comparatively standardized
We will also examine the NoSQL databases and the Hierarchical and Network models
Of course, we will also learn SQL
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