<s>
.QL	B-Language
(	O
pronounced	O
"	O
dot-cue-el	O
"	O
)	O
is	O
an	O
object-oriented	B-Language
query	O
language	O
used	O
to	O
retrieve	O
data	O
from	O
relational	O
database	B-Application
management	I-Application
systems	I-Application
.	O
</s>
<s>
It	O
is	O
reminiscent	O
of	O
the	O
standard	O
query	O
language	O
SQL	B-Language
and	O
the	O
object-oriented	B-Language
programming	I-Language
language	I-Language
Java	B-Language
.	O
</s>
<s>
.QL	B-Language
is	O
an	O
object-oriented	B-Language
variant	O
of	O
a	O
logical	O
query	O
language	O
called	O
Datalog	B-Language
.	O
</s>
<s>
Hierarchical	O
data	O
can	O
therefore	O
be	O
naturally	O
queried	O
in	O
.QL	B-Language
in	O
a	O
recursive	O
manner	O
.	O
</s>
<s>
Queries	O
written	O
in	O
.QL	B-Language
are	O
optimised	O
,	O
compiled	O
into	O
SQL	B-Language
and	O
can	O
then	O
be	O
executed	O
on	O
any	O
major	O
relational	O
database	B-Application
management	I-Application
system	I-Application
.	O
</s>
<s>
.QL	B-Language
query	O
language	O
is	O
being	O
used	O
in	O
SemmleCode	B-Language
to	O
query	O
a	O
relational	O
representation	O
of	O
Java	B-Language
programs	O
.	O
</s>
<s>
.QL	B-Language
is	O
developed	O
at	O
Semmle	B-Language
Limited	O
and	O
is	O
based	O
on	O
the	O
company	O
's	O
proprietary	O
technology	O
.	O
</s>
<s>
.QL	B-Language
has	O
several	O
language	O
features	O
to	O
make	O
queries	O
concise	O
,	O
intuitive	O
and	O
reusable	O
:	O
</s>
<s>
The	O
sample	O
query	O
below	O
illustrates	O
use	O
of	O
.QL	B-Language
to	O
query	O
a	O
Java	B-Language
program	O
.	O
</s>
