DATABASE EVOLUTION & ENVIRONMENT Chandra S. Amaravadi
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DATABASE
EVOLUTION &
ENVIRONMENT
Chandra S. Amaravadi
PREVIOUSLY, IN INTRODUCTION
Database importance
Basic data organization concepts
Database concept
Development cycle
Example application
In our introduction we discussed the following:
IN THIS DISCUSSION Evolution
The database approach
Database architecture
DBMS architecture
DBMS environment
DBMS EVOLUTION
Introduction of business computers in 1950’s, ‘60’s
Used in TP applications (file processing)
Led to problems of file processing (see next)
Academic formulations of DBMS concepts
Standardization of DBMS concepts (by CODASYL 1971)
Hierarchical and network databases
EVOLUTION OF DBMS
DBMS evolved out of file processing environment:
FILE PROCESSING APPROACH
File processing evolved from transaction environment of the 1950’s. It involves application managing its own files.
Application1Application1
File1File1
Application2Application2
File2File2
EVOLUTION OF DBMS..
Following are the problems caused by file processing:
Uncontrolled redundancy
Program data dependence
Program maintenance
Poor data quality
Inability to get reports
Application backlog
EVOLUTION OF DBMS..PROBLEMS CAUSED BY FILE PROCESSING
Uncontrolled redundancy – Same data is duplicated in multiple files
Program data dependence – Application programs dependent on
structure of the data
Program maintenance – Too much effort spent in changing programs
to accommodate changes in file structures.
Poor data quality – Redundancy can often lead to inconsistent
updates of the data, leading in turn to problems of data quality.
Inability to get reports – Since each file was tied to a particular
program, it was hard to get reports involving multiple files
Application backlog – Managers’ requests for report led application
programmers to write new applications to fulfill the request. They
were typically behind in fulfilling the requests, hence
the backlog.
ApplicationsApplications
File handling File handling
routinesroutines
FilesFiles
ApplicationsApplications
DBMSDBMS
FilesFiles
Application +Application +
Data managementData management
FilesFiles
FROM FILE PROCESSING TO DBMS..
EVOLUTION OF DBMS.. (FYI)Developments in DBMS include:
Codd’s PaperIn 1970
Ingres in 1971 Oracle in 1977
Britton Lee Founded in 1979
Sybase in 1986
Teradata corp.
SAP
EVOLUTION OF DBMS.. (FYI)
THE DBMS/DB APPROACH
THE DBMS/DB APPROACH
cust.cust.
emp.emp.
Enterprise
Entity classes
Data model
Cust.
Emp.
Data base
THE DBMS/DB APPROACH
Integrated conceptualization of the data (??)
Organized design of database
Centralized management of data
System controlled access
Checks on data quality
Retrieve data easily (reports, queries)
Application1Application1
File1File1
Application2Application2
File2File2
GETTING INFORMATION
FROM A DATABASE
GETTING INFORMATIONIN FILE PROCESSING
CUSTOMER ACCTS. LOANS
CROSS REFERENCE
REPORT
ACCT. DATA LOAN DATA
GETTING INFORMATIONIN DATABASE APPROACH
Reports
Queries [SQL, QBE]
Views [forms that display]
Data from the database can be obtained through:
GETTING INFORMATIONIN DATABASE APPROACH
ACCT
LOAN
How can we get Acct &Loan info. inone report?
ACCT # NAME DT. OPENED BALANCE
8895 Smith 4/16/11 $35,000
8896 Farley 4/22/07 $300
8897 Gomez 1/10/09 $2000
LID AMOUT INT. RATE BALANCE
9978 $6,000 6.0% $2,440
9979 $5,000 7.1% $5,000
9992 $1,000 8.5% $400
GETTING INFORMATION FROM MULTIPLE TABLES
Two rules for multi-table SQL
1. In the Select part, precede each attribute name by name of table e.g. Select Acct.name, Loan.LID
2. In the Where part, equate values of common key from both tables e.g. ..where Acct.Acct# = Loan.Acct#
Write a query to list Name, balance, loan amt and balance for all customers.
When data is retrieved from multiple tables, thefollowing are the rules for writing queries:
DATABASE & DBMS
ARCHITECTURE
THREE-SCHEMA ARCHITECTURE
A prescription for how data should be stored
(in a macro sense)
Provides benefits of logical and physical
independence
Lacking in file processing approach
*Standards Planning and Requirements Committee
An architecture for databases introduced by ANSI/SPARC*
Conceptual/
Base table (schema)
THE THREE FORMS OF DATA
External (view)
Internal/
Hardware level
(file organization)
111000110
11101001
11101001
THE THREE FORMS OF DATA..
External/ --- The view of data as seen by a user/
application program (views). Conceptual/ --- The view as seen by a database
designer (base table)
Internal --- The view of data as it is stored
internallyThese three levels provide logical and physical data independence, the
ability to change the structure of the data and the ability to change the
internal storage structure, independently of the application program.
THREE-SCHEMA ARCHITECTURE..
BaseBaseTableTable
BaseBaseTableTable
BaseBaseTableTable
View1View1 View2View2External
Conceptual/
Logical
Physical/
Internal
Data is organized at three levels to provide logical/physical ______ ________________.
THREE-SCHEMA ARCHITECTURE..
Basic concept is that of a view
A view is the way data is presented
It is a subset of the data
The data resides in base tables
A base table contains information about an Eclass
Applns. access data via views
Views are created in SQL or by forms/reports
Create table
Alter table
Create index
drop index
DBMS Facilities
ConceptualConceptualConceptualConceptual
InternalInternalInternalInternal
ExternalExternalExternalExternal
Models
Schemas
File
Organizations
Views
THE THREE TYPES OF MODELS
Create view
Drop view
___________ , ___________ and ____ __________ are examples of modelscorresponding to the three levels of the three schema architecture.
D B M S KernelD B M S Kernel
D B M S KernelD B M S Kernel
MAJOR COMPONENTS OF DBMS
Export/ImportExport/Import
Data Defn.Data Defn. SQLSQL
Prog. Language Interface
Prog. Language Interface
DataDiction-
ary
DataDiction-
ary
Screen/ReportGen.
Screen/ReportGen.
Appln.Gen.
Appln.Gen.
DBMS COMPONENTS..Data definition – the facility through which schema is defined. (how new tables are created).SQL interface – the facility through which SQL commands are typed in.Programming language interface – the facility which processes SQL commands embedded in application program. Also known
as the host language interface. Data dictionary – the facility that records details about the schema, reports, data entry forms etc.Screen & reports- the facility through which data entry screens and reports are created.Appln. Generation- the facility through which applications are created.Export/Import -- the facility through which files can be imported/exported in different DBMS formats.DBMS Kernel -- the actual programs which interact with the O/S and carry out data I/O. ODBC -- Open Database Connectivity – middleware to take SQL commands & return data.
THE DIFFERENT CLASSES OF USERS IN A DBMS
UsersDevelopersAdministrators
DBMS
DataAdministration
DBMSDBMSClientClient
DBMSDBMSClientClient
LegacyLegacyApplicationsApplications
LegacyLegacyApplicationsApplications
EnterpriseEnterpriseApplicationsApplications
EnterpriseEnterpriseApplicationsApplications
DBMS/SQLServer
AN INTEGRATED DATABASE ENVIRONMENT
Developers End Users
Dir.Dir.ServerServer
Database
Directory server- a component that stores user names & PW (aka active directory or LDAP).
DBMS client- a front end to provide access to DBMS functionality.
Enterprise applications- various information systems of the organization.
Legacy applications – older, mainframe-based applications.
DBMS Server - a DBMS that can run queries (does not have user interface, only program interface).
Database- collection of information
COMPONENTS OF AN INTEGRATED DATABASE ENVIRONMENT
DIFFERENT TYPES OF ENTERPRISE DATABASE ENVIRONMENTS
Single tier, single user, direct DBMS access
SERVER
CLIENT Two tier, multi-user, client server
SERVER
CLIENT
Middleware
three tier, multi-user, client server with middleware
SINGLE
USER
DataWarehouse
OLAP
Decisions
Data Mining
InternalDatabase
InternalDatabase
ExternalDatabase
DATA WAREHOUSES, OLAP & DATA MINING
Data warehousing refers to the use of high speed/high capacity servers to store historical data and to make this available to decision makers.
OLAP is the process of analyzing historical data on a PC using mult-dimensional databases (i.e. non-relational databases) using aggregate data operations.
Data mining refers to identification of patterns from data.
Business Intelligence
What organization standardized DBMS concepts?
Who was the chief architect of relational systems?
What data-related functions were performed in the
file processing approach?
What are some of the basic features of a DBMS?
What is the smallest unit of data in a database?
Define the terms: schema, view, database, three-schema
architecture.
How is redundancy minimized in the database approach?
What are advantages of the 3-schema architecture?
What is the difference between 2-tier & 3-tier environments?
DISCUSSION
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