History of Database Systems
By
Kaushalya Dharmarathna(030087)
Sandun Weerasinghe(040417)
Early Manual System
{ Before-1950s
z Data was stored as paper records.
z Lot of man power involved.
z Lot of time was wasted.
e.g. when searching
z Therefore inefficient.
1
Revolution began
{ 1950s and early 1960s:
z Data processing using magnetic tapes for
storage
z Tapes provide only sequential access
z Punched cards for input
{ Late 1960s and 1970s:
z Hard disks allow direct access to data
z Data stored in files
z Known as File Processing System
File based systems
{ Adequate for small applications
{ Drawbacks
z Separation and isolation of data
{ Each program maintains its own set of
data.
{ Users of one program may be
unaware of potentially useful data
held by other programs.
2
File based systems (contd.)
z Duplication of data
{ Same data is held by different
locations.
{ Wasted space and potentially different
values and/or different formats for the
same item.
z Data dependence
{ File structure is defined in the program
code.
File based systems (contd.)
z Incompatible file formats
{ Programs are written in different
languages, and so cannot easily access
each others files.
z Fixed Queries/Proliferation of
application programs
{ Programs are written to satisfy particular
functions.
{ Any new requirement needs a new
program.
3
Database Approach
{ Arose because:
z Definition of data was embedded in application
programs, rather than being stored separately
and independently.
z No control over access and manipulation of
data beyond that imposed by application
programs.
{ Result:
z The database and Database Management
System (DBMS).
Database Management Systems
(DBMS)
1960s Hierarchical Network
1970s Relational
1990s Object-oriented Object-relational
1995+ Java XML CMDB Mobile
IMDB Embedded
4
Hierarchical Model
{ Well suited for data which are in some
way related
{ Hierarchically begin with a strictly
defined tree of data nodes
{ Each node can contain some identifying
data, plus a set of subnodes of a specific
child type
Hierarchical Model (Contd.)
5
Network Model
{ Supported more complex relations
{ Physical file pointers were used to
model the relations between files
{ Relations had to be decide in
advance
{ Most suitable for large databases
with well defined queries and well-
defined applications.
Network Model (Contd.)
Authors
Subjects Books
Publishers
6
Relational Model (1970s)
{ E.F. Codd introduced the relational
model in 1970
{ Provides a conceptually simple
model for data as relations
(typically considered tables) with
all data visible.
{ DB2 from IBM is the first DBMS
product based on the relational
model
Relational Model (Contd.)
7
Relational Model (Contd.)
{ Other DBMS based on the relational
model were developed in the late
1980s
{ Today, DB2, Oracle, and SQL Server
are the most prominent commercial
DBMS products based on the
relational model
Object Oriented Data Model (1990s)
{ Goal of OODBMS is to store object-
oriented programming objects in a
database without having to
transform them into relational
format.
{ Extend the entity-relationship data
model by including encapsulation,
methods and object identity
8
Object-relational models
{ Extend the relational data model by
including object orientation and
constructs to deal with added data types.
{ Allow attributes of tuples to have complex
types, including non-atomic values such
as nested relations.
{ Preserve relational foundations, in
particular the declarative access to data,
while extending modeling power.
Modern Database Management
Systems
{ DBMS are large complex pieces of
software designed specifically for
the efficient management of data.
{ Examples:
z Oracle (Oracle Corporation)
z Ingres (Computer Associates)
z SQL Server (Microsoft Corporation)
z Access (Microsoft Corporation)
z IMS, DB2 (IBM)
z And many more
