<s>
PL/pgSQL	B-Language
(	O
Procedural	O
Language/PostgreSQL	O
)	O
is	O
a	O
procedural	B-Application
programming	I-Application
language	I-Application
supported	O
by	O
the	O
PostgreSQL	B-Application
ORDBMS	B-General_Concept
.	O
</s>
<s>
It	O
closely	O
resembles	O
Oracle	B-General_Concept
's	O
PL/SQL	B-Language
language	O
.	O
</s>
<s>
Implemented	O
by	O
Jan	B-Language
Wieck	I-Language
,	O
PL/pgSQL	B-Language
first	O
appeared	O
with	O
PostgreSQL	B-Application
6.4	O
,	O
released	O
on	O
October	O
30	O
,	O
1998	O
.	O
</s>
<s>
Version	O
9	O
also	O
implements	O
some	O
ISO	O
SQL/PSM	B-Language
features	O
,	O
like	O
overloading	O
of	O
SQL-invoked	O
functions	O
and	O
procedures	O
.	O
</s>
<s>
PL/pgSQL	B-Language
,	O
as	O
a	O
fully	O
featured	O
programming	O
language	O
,	O
allows	O
much	O
more	O
procedural	B-Application
control	O
than	O
SQL	B-Language
,	O
including	O
the	O
ability	O
to	O
use	O
loops	O
and	O
other	O
control	O
structures	O
.	O
</s>
<s>
SQL	B-Language
statements	O
and	O
triggers	O
can	O
call	O
functions	O
created	O
in	O
the	O
PL/pgSQL	B-Language
language	O
.	O
</s>
<s>
The	O
design	O
of	O
PL/pgSQL	B-Language
aimed	O
to	O
allow	O
PostgreSQL	B-Application
users	O
to	O
perform	O
more	O
complex	O
operations	O
and	O
computations	O
than	O
SQL	B-Language
,	O
while	O
providing	O
ease	O
of	O
use	O
.	O
</s>
<s>
PL/pgSQL	B-Language
is	O
one	O
of	O
the	O
programming	O
languages	O
included	O
in	O
the	O
standard	O
PostgreSQL	B-Application
distribution	O
,	O
the	O
others	O
being	O
,	O
PL/Perl	O
and	O
PL/Python	O
.	O
</s>
<s>
PostgreSQL	B-Application
uses	O
Bison	B-Application
as	O
its	O
parser	O
,	O
</s>
<s>
making	O
it	O
easy	O
to	O
port	O
many	O
open-source	B-License
languages	O
,	O
as	O
well	O
as	O
to	O
reuse	O
code	O
.	O
</s>
<s>
The	O
SQL/PSM	B-Language
language	O
is	O
specified	O
by	O
an	O
ISO	O
standard	O
,	O
but	O
is	O
also	O
inspired	O
by	O
Oracle	B-General_Concept
's	O
PL/SQL	B-Language
and	O
PL/pgPL/SQL	O
,	O
so	O
there	O
are	O
few	O
differences	O
.	O
</s>
<s>
The	O
main	O
features	O
of	O
PSM	O
that	O
differ	O
from	O
PL/pgSQL	B-Language
:	O
</s>
<s>
Declaration	O
of	O
variables	O
should	O
be	O
based	O
on	O
SQL	B-Language
query	O
result	O
.	O
</s>
<s>
All	O
three	O
languages	O
(	O
Oracle	B-General_Concept
PL/SQL	B-Language
,	O
PostgreSQL	B-Application
PL/pgSQL	B-Language
and	O
ISO	O
SQL/PSM	B-Language
)	O
are	O
originally	O
descended	O
from	O
the	O
Ada	B-Language
programming	I-Language
language	I-Language
.	O
</s>
<s>
Formal	O
pseudo-language	O
for	O
documentation	O
can	O
be	O
embedded	O
in	O
SQL	B-Language
and	O
PL/pgSQL	B-Language
scripts	O
.	O
</s>
<s>
This	O
documentation	O
is	O
then	O
processed	O
by	O
a	O
documentation	B-Protocol
generator	I-Protocol
—	O
an	O
external	O
tool	O
which	O
extracts	O
data	O
and	O
generates	O
hypertext	O
.	O
</s>
<s>
Since	O
PL/SQL	B-Language
:	O
supports	O
some	O
of	O
these	O
tools	O
,	O
PL/pgSQL	B-Language
is	O
expected	O
to	O
provide	O
full	O
or	O
partial	O
support	O
as	O
well	O
.	O
</s>
<s>
ToolFull	O
PL/pgSQLJavadoc	O
styleOther	O
stylePL/pgSQL	O
projects	O
using	O
itDocument	O
!	O
</s>
<s>
Other	O
documentation	O
tools	O
:	O
Doxygen	B-Language
,	O
DBScribe	O
,	O
HyperSQL	O
,	O
Universal	O
Report	O
.	O
</s>
