<s>
An	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
(	O
ORD	O
)	O
,	O
or	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	B-Application
management	I-Application
system	I-Application
(	O
ORDBMS	B-General_Concept
)	O
,	O
is	O
a	O
database	B-Application
management	I-Application
system	I-Application
(	O
DBMS	O
)	O
similar	O
to	O
a	O
relational	B-Application
database	I-Application
,	O
but	O
with	O
an	O
object-oriented	B-Application
database	I-Application
model	I-Application
:	O
objects	O
,	O
classes	O
and	O
inheritance	B-Language
are	O
directly	O
supported	O
in	O
database	B-Application
schemas	I-Application
and	O
in	O
the	O
query	B-Language
language	I-Language
.	O
</s>
<s>
In	O
addition	O
,	O
just	O
as	O
with	O
pure	O
relational	O
systems	O
,	O
it	O
supports	O
extension	O
of	O
the	O
data	B-Application
model	I-Application
with	O
custom	O
data	O
types	O
and	O
methods	B-Language
.	O
</s>
<s>
An	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
can	O
be	O
said	O
to	O
provide	O
a	O
middle	O
ground	O
between	O
relational	B-Application
databases	I-Application
and	O
object-oriented	B-Application
databases	I-Application
.	O
</s>
<s>
In	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
databases	I-General_Concept
,	O
the	O
approach	O
is	O
essentially	O
that	O
of	O
relational	B-Application
databases	I-Application
:	O
the	O
data	O
resides	O
in	O
the	O
database	O
and	O
is	O
manipulated	O
collectively	O
with	O
queries	O
in	O
a	O
query	B-Language
language	I-Language
;	O
at	O
the	O
other	O
extreme	O
are	O
OODBMSes	O
in	O
which	O
the	O
database	O
is	O
essentially	O
a	O
persistent	O
object	O
store	O
for	O
software	O
written	O
in	O
an	O
object-oriented	B-Language
programming	I-Language
language	I-Language
,	O
with	O
a	O
programming	O
API	B-General_Concept
for	O
storing	O
and	O
retrieving	O
objects	O
,	O
and	O
little	O
or	O
no	O
specific	O
support	O
for	O
querying	O
.	O
</s>
<s>
The	O
basic	O
need	O
of	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
arises	O
from	O
the	O
fact	O
that	O
both	O
Relational	O
and	O
Object	B-Application
database	I-Application
have	O
their	O
individual	O
advantages	O
and	O
drawbacks	O
.	O
</s>
<s>
The	O
isomorphism	O
of	O
the	O
relational	B-Application
database	I-Application
system	O
with	O
a	O
mathematical	O
relation	O
allows	O
it	O
to	O
exploit	O
many	O
useful	O
techniques	O
and	O
theorems	O
from	O
set	O
theory	O
.	O
</s>
<s>
But	O
these	O
types	O
of	O
databases	B-Application
are	O
not	O
optimal	O
for	O
certain	O
kinds	O
of	O
applications	O
.	O
</s>
<s>
An	O
object	B-Application
oriented	I-Application
database	I-Application
model	O
allows	O
containers	O
like	O
sets	O
and	O
lists	O
,	O
arbitrary	O
user-defined	O
datatypes	O
as	O
well	O
as	O
nested	O
objects	O
.	O
</s>
<s>
But	O
object	B-Application
databases	I-Application
,	O
unlike	O
relational	O
do	O
not	O
provide	O
any	O
mathematical	O
base	O
for	O
their	O
deep	O
analysis	O
.	O
</s>
<s>
The	O
basic	O
goal	O
for	O
the	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
is	O
to	O
bridge	O
the	O
gap	O
between	O
relational	B-Application
databases	I-Application
and	O
the	O
object-oriented	B-Application
modeling	I-Application
techniques	O
used	O
in	O
programming	O
languages	O
such	O
as	O
Java	B-Language
,	O
C++	B-Language
,	O
Visual	B-Language
Basic	I-Language
.NET	I-Language
or	O
C#	B-Application
.	O
</s>
<s>
However	O
,	O
a	O
more	O
popular	O
alternative	O
for	O
achieving	O
such	O
a	O
bridge	O
is	O
to	O
use	O
a	O
standard	O
relational	B-Application
database	I-Application
systems	O
with	O
some	O
form	O
of	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
mapping	I-General_Concept
(	O
ORM	O
)	O
software	O
.	O
</s>
<s>
Whereas	O
traditional	O
RDBMS	O
or	O
SQL-DBMS	O
products	O
focused	O
on	O
the	O
efficient	O
management	O
of	O
data	O
drawn	O
from	O
a	O
limited	O
set	O
of	O
data-types	O
(	O
defined	O
by	O
the	O
relevant	O
language	O
standards	O
)	O
,	O
an	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
DBMS	O
allows	O
software	O
developers	O
to	O
integrate	O
their	O
own	O
types	O
and	O
the	O
methods	B-Language
that	O
apply	O
to	O
them	O
into	O
the	O
DBMS	O
.	O
</s>
<s>
The	O
ORDBMS	B-General_Concept
(	O
like	O
ODBMS	B-Application
or	O
OODBMS	B-Application
)	O
is	O
integrated	O
with	O
an	O
object-oriented	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
The	O
characteristic	O
properties	O
of	O
ORDBMS	B-General_Concept
are	O
1	O
)	O
complex	O
data	O
,	O
2	O
)	O
type	B-Language
inheritance	I-Language
,	O
and	O
3	O
)	O
object	O
behavior	O
.	O
</s>
<s>
Complex	O
data	O
creation	O
in	O
most	O
SQL	B-Language
ORDBMSs	O
is	O
based	O
on	O
preliminary	O
schema	B-Application
definition	O
via	O
the	O
user-defined	B-Language
type	I-Language
(	O
UDT	O
)	O
.	O
</s>
<s>
Hierarchy	O
within	O
structured	O
complex	O
data	O
offers	O
an	O
additional	O
property	O
,	O
type	B-Language
inheritance	I-Language
.	O
</s>
<s>
That	O
is	O
,	O
a	O
structured	B-Language
type	I-Language
can	O
have	O
subtypes	O
that	O
reuse	O
all	O
of	O
its	O
attributes	O
and	O
contain	O
additional	O
attributes	O
specific	O
to	O
the	O
subtype	O
.	O
</s>
<s>
In	O
object-oriented	B-Language
programming	I-Language
(	O
OOP	O
)	O
,	O
object	O
behavior	O
is	O
described	O
through	O
the	O
methods	B-Language
(	O
object	O
functions	O
)	O
.	O
</s>
<s>
The	O
methods	B-Language
denoted	O
by	O
one	O
name	O
are	O
distinguished	O
by	O
the	O
type	O
of	O
their	O
parameters	O
and	O
type	O
of	O
objects	O
for	O
which	O
they	O
attached	O
(	O
method	O
signature	O
)	O
.	O
</s>
<s>
The	O
OOP	O
languages	O
call	O
this	O
the	O
polymorphism	B-Application
principle	O
,	O
which	O
briefly	O
is	O
defined	O
as	O
"	O
one	O
interface	O
,	O
many	O
implementations	O
"	O
.	O
</s>
<s>
Other	O
OOP	O
principles	O
,	O
inheritance	B-Language
and	O
encapsulation	B-Application
,	O
are	O
related	O
both	O
to	O
methods	B-Language
and	O
attributes	O
.	O
</s>
<s>
Method	O
inheritance	B-Language
is	O
included	O
in	O
type	B-Language
inheritance	I-Language
.	O
</s>
<s>
Encapsulation	B-Application
in	O
OOP	O
is	O
a	O
visibility	O
degree	O
declared	O
,	O
for	O
example	O
,	O
through	O
the	O
public	O
,	O
private	O
and	O
protected	O
access	O
modifiers	O
.	O
</s>
<s>
Object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
management	O
systems	O
grew	O
out	O
of	O
research	O
that	O
occurred	O
in	O
the	O
early	O
1990s	O
.	O
</s>
<s>
That	O
research	O
extended	O
existing	O
relational	B-Application
database	I-Application
concepts	O
by	O
adding	O
object	O
concepts	O
.	O
</s>
<s>
Probably	O
the	O
most	O
notable	O
research	O
project	O
,	O
Postgres	B-Application
(	O
UC	O
Berkeley	O
)	O
,	O
spawned	O
two	O
products	O
tracing	O
their	O
lineage	O
to	O
that	O
research	O
:	O
Illustra	B-Application
and	O
PostgreSQL	B-Application
.	O
</s>
<s>
These	O
included	O
Illustra	B-Application
(	O
Illustra	B-Application
Information	O
Systems	O
,	O
acquired	O
by	O
Informix	O
Software	O
,	O
which	O
was	O
in	O
turn	O
acquired	O
by	O
IBM	O
)	O
,	O
Omniscience	O
(	O
Omniscience	O
Corporation	O
,	O
acquired	O
by	O
Oracle	B-Application
Corporation	I-Application
and	O
became	O
the	O
original	O
Oracle	B-General_Concept
Lite	O
)	O
,	O
and	O
UniSQL	O
(	O
UniSQL	O
,	O
Inc.	O
,	O
acquired	O
by	O
KCOMS	O
)	O
.	O
</s>
<s>
Ukrainian	O
developer	O
Ruslan	O
Zasukhin	O
,	O
founder	O
of	O
Paradigma	O
Software	O
,	O
Inc.	O
,	O
developed	O
and	O
shipped	O
the	O
first	O
version	O
of	O
Valentina	O
database	O
in	O
the	O
mid-1990s	O
as	O
a	O
C++	B-Language
SDK	B-Application
.	O
</s>
<s>
By	O
the	O
next	O
decade	O
,	O
PostgreSQL	B-Application
had	O
become	O
a	O
commercially	O
viable	O
database	O
,	O
and	O
is	O
the	O
basis	O
for	O
several	O
current	O
products	O
that	O
maintain	O
its	O
ORDBMS	B-General_Concept
features	O
.	O
</s>
<s>
Computer	O
scientists	O
came	O
to	O
refer	O
to	O
these	O
products	O
as	O
"	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
management	O
systems	O
"	O
or	O
ORDBMSs	O
.	O
</s>
<s>
Many	O
of	O
the	O
ideas	O
of	O
early	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
efforts	O
have	O
largely	O
become	O
incorporated	O
into	O
SQL:1999	B-Language
via	O
structured	B-Language
types	I-Language
.	O
</s>
<s>
In	O
fact	O
,	O
any	O
product	O
that	O
adheres	O
to	O
the	O
object-oriented	B-Language
aspects	O
of	O
SQL:1999	B-Language
could	O
be	O
described	O
as	O
an	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
management	O
product	O
.	O
</s>
<s>
For	O
example	O
,	O
IBM	B-Application
Db2	I-Application
,	O
Oracle	B-General_Concept
database	I-General_Concept
,	O
and	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
make	O
claims	O
to	O
support	O
this	O
technology	O
and	O
do	O
so	O
with	O
varying	O
degrees	O
of	O
success	O
.	O
</s>
<s>
An	O
RDBMS	O
might	O
commonly	O
involve	O
SQL	B-Language
statements	O
such	O
as	O
these	O
:	O
</s>
<s>
Most	O
SQL	B-Language
databases	I-Language
allow	O
the	O
crafting	O
of	O
custom	O
functions	O
,	O
which	O
would	O
allow	O
the	O
query	O
to	O
appear	O
as	O
:	O
</s>
<s>
In	O
an	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
,	O
one	O
might	O
see	O
something	O
like	O
this	O
,	O
with	O
user-defined	O
data-types	O
and	O
expressions	O
such	O
as	O
BirthDay( )	O
:	O
</s>
<s>
The	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
model	O
can	O
offer	O
another	O
advantage	O
in	O
that	O
the	O
database	O
can	O
make	O
use	O
of	O
the	O
relationships	O
between	O
data	O
to	O
easily	O
collect	O
related	O
records	O
.	O
</s>
<s>
In	O
an	O
address	B-Operating_System
book	I-Operating_System
application	O
,	O
an	O
additional	O
table	O
would	O
be	O
added	O
to	O
the	O
ones	O
above	O
to	O
hold	O
zero	O
or	O
more	O
addresses	O
for	O
each	O
customer	O
.	O
</s>
<s>
The	O
same	O
query	O
in	O
an	O
object	B-General_Concept
–	I-General_Concept
relational	I-General_Concept
database	I-General_Concept
appears	O
more	O
simply	O
:	O
</s>
