<s>
EJB	B-Language
QL	I-Language
or	O
EJB-QL	O
is	O
a	O
portable	O
database	B-Language
query	I-Language
language	I-Language
for	O
Enterprise	B-Language
Java	I-Language
Beans	I-Language
.	O
</s>
<s>
It	O
was	O
used	O
in	O
Java	B-Language
EE	I-Language
applications	O
.	O
</s>
<s>
Compared	O
to	O
SQL	B-Language
,	O
however	O
,	O
it	O
is	O
less	O
complex	O
but	O
less	O
powerful	O
as	O
well	O
.	O
</s>
<s>
The	O
language	O
has	O
been	O
inspired	O
,	O
especially	O
EJB3-QL	O
,	O
by	O
the	O
native	O
Hibernate	O
Query	B-Language
Language	I-Language
.	O
</s>
<s>
In	O
EJB3	O
It	O
has	O
been	O
mostly	O
replaced	O
by	O
the	O
Java	B-Language
Persistence	I-Language
Query	I-Language
Language	I-Language
.	O
</s>
<s>
EJB	B-Language
QL	I-Language
is	O
a	O
database	B-Language
query	I-Language
language	I-Language
similar	O
to	O
SQL	B-Language
.	O
</s>
<s>
The	O
used	O
queries	O
are	O
somewhat	O
different	O
from	O
relational	O
SQL	B-Language
,	O
as	O
it	O
uses	O
a	O
so-called	O
"	O
abstract	O
schema	O
"	O
of	O
the	O
enterprise	B-Language
beans	I-Language
instead	O
of	O
the	O
relational	O
model	O
.	O
</s>
<s>
In	O
other	O
words	O
,	O
EJB	B-Language
QL	I-Language
queries	O
do	O
not	O
use	O
tables	O
and	O
their	O
components	O
,	O
but	O
enterprise	B-Language
beans	I-Language
,	O
their	O
persistent	O
state	O
,	O
and	O
their	O
relationships	O
.	O
</s>
<s>
The	O
result	O
of	O
an	O
SQL	B-Language
query	O
is	O
a	O
set	O
of	O
rows	O
with	O
a	O
fixed	O
number	O
of	O
columns	O
.	O
</s>
<s>
The	O
result	O
of	O
an	O
EJB	B-Language
QL	I-Language
query	O
is	O
either	O
a	O
single	O
object	O
,	O
a	O
collection	O
of	O
entity	O
objects	O
of	O
a	O
given	O
type	O
,	O
or	O
a	O
collection	O
of	O
values	O
retrieved	O
from	O
CMP	O
fields	O
.	O
</s>
<s>
One	O
has	O
to	O
understand	O
the	O
data	O
model	O
of	O
enterprise	B-Language
beans	I-Language
in	O
order	O
to	O
write	O
effective	O
queries	O
.	O
</s>
