<s>
Microsoft	B-Operating_System
SQL	I-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
(	O
EOL	O
,	O
See	O
SQL	O
Express	O
)	O
(	O
SQL	B-Operating_System
CE	I-Operating_System
)	O
is	O
a	O
compact	B-General_Concept
relational	B-Application
database	I-Application
produced	O
by	O
Microsoft	O
for	O
applications	O
that	O
run	O
on	O
mobile	O
devices	O
and	O
desktops	O
.	O
</s>
<s>
Prior	O
to	O
the	O
introduction	O
of	O
the	O
desktop	O
platform	O
,	O
it	O
was	O
known	O
as	O
SQL	O
Server	O
for	O
Windows	B-Operating_System
CE	I-Operating_System
and	O
SQL	B-Operating_System
Server	I-Operating_System
Mobile	I-Operating_System
Edition	I-Operating_System
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
targets	O
occasionally	O
connected	O
applications	O
and	O
applications	O
with	O
an	O
embedded	O
database	O
.	O
</s>
<s>
An	O
ODBC	B-Application
driver	O
for	O
SQL	B-Operating_System
CE	I-Operating_System
does	O
not	O
exist	O
,	O
nor	O
is	O
one	O
planned	O
.	O
</s>
<s>
Native	O
applications	O
may	O
use	O
SQL	B-Operating_System
CE	I-Operating_System
via	O
OLE	B-Language
DB	I-Language
.	O
</s>
<s>
The	O
latest	O
,	O
and	O
last	O
,	O
release	O
is	O
the	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
4.0	O
.	O
</s>
<s>
In	O
February	O
2013	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
Edition	I-Operating_System
had	O
been	O
deprecated	O
;	O
no	O
new	O
versions	O
or	O
updates	O
are	O
planned	O
,	O
although	O
Microsoft	O
continued	O
to	O
support	O
the	O
product	O
until	O
July	O
2021	O
.	O
</s>
<s>
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
shares	O
a	O
common	O
API	B-Application
with	O
the	O
other	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
editions	O
.	O
</s>
<s>
It	O
also	O
includes	O
ADO.NET	B-Device
providers	I-Device
for	O
data	O
access	O
using	O
ADO.NET	B-Device
APIs	B-Application
,	O
and	O
built-in	O
synchronization	O
capabilities	O
,	O
as	O
well	O
as	O
support	O
for	O
LINQ	B-Language
and	O
Entity	B-Application
Framework	I-Application
.	O
</s>
<s>
Future	O
releases	O
will	O
unify	O
the	O
synchronization	O
capabilities	O
with	O
Microsoft	B-Device
Synchronization	I-Device
Services	I-Device
.	O
</s>
<s>
Unlike	O
other	O
editions	O
of	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
SQL	B-Operating_System
CE	I-Operating_System
runs	O
in-process	O
with	O
the	O
application	O
which	O
is	O
hosting	O
it	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
is	O
optimized	O
for	O
an	O
architecture	O
where	O
all	O
applications	O
share	O
the	O
same	O
memory	O
pool	O
.	O
</s>
<s>
Windows	O
Store	O
apps	O
for	O
Windows	O
8	O
cannot	O
use	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
edition	I-Operating_System
,	O
or	O
any	O
other	O
edition	O
of	O
SQL	O
Server	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
databases	O
can	O
support	O
ACID-compliance	O
,	O
but	O
do	O
not	O
meet	O
the	O
durability	O
requirement	O
by	O
default	O
because	O
AutoFlush	O
buffers	O
changes	O
in	O
memory	O
(	O
including	O
enlisted	O
ambient	O
transactions	O
and	O
explicit	O
SQL	B-Operating_System
CE	I-Operating_System
transactions	O
that	O
do	O
not	O
override	O
the	O
Commit( )	O
call	O
with	O
an	O
CommitMode.Immediate	O
value	O
)	O
.	O
</s>
<s>
Like	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
SQL	B-Operating_System
CE	I-Operating_System
supports	O
transactions	O
,	O
referential	O
integrity	O
constraints	O
,	O
locking	O
as	O
well	O
as	O
multiple	O
connections	O
to	O
the	O
database	O
store	O
.	O
</s>
<s>
The	O
current	O
release	O
does	O
not	O
support	O
stored	B-General_Concept
procedures	I-General_Concept
or	O
native	O
XML	B-Protocol
data	O
type	O
either	O
.	O
</s>
<s>
It	O
uses	O
a	O
subset	O
of	O
T-SQL	B-Language
for	O
querying	O
and	O
due	O
to	O
lack	O
of	O
XML	B-Protocol
support	O
,	O
XQuery	B-Language
is	O
not	O
supported	O
either	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
databases	O
also	O
support	O
indexing	O
,	O
as	O
well	O
as	O
support	O
remote	O
data	O
replication	O
(	O
local	O
caching	O
of	O
data	O
in	O
remote	O
databases	O
)	O
and	O
merge	O
replication	O
(	O
bidirectional	O
synchronization	O
with	O
master	O
databases	O
)	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
databases	O
can	O
be	O
created	O
and	O
managed	O
from	O
Microsoft	B-Application
Visual	I-Application
Studio	I-Application
and	O
some	O
older	O
versions	O
of	O
SQL	B-Device
Server	I-Device
Management	I-Device
Studio	I-Device
as	O
well	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
databases	O
reside	O
in	O
a	O
single	O
.sdf	O
file	O
,	O
which	O
can	O
be	O
up	O
to	O
4	O
GB	O
in	O
size	O
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
runtime	O
mediates	O
concurrent	O
multi-user	O
access	O
to	O
the	O
.sdf	O
file	O
.	O
</s>
<s>
The	O
.sdf	O
file	O
can	O
simply	O
be	O
copied	O
to	O
the	O
destination	O
system	O
for	O
deployment	O
,	O
or	O
be	O
deployed	O
through	O
ClickOnce	B-Application
.	O
</s>
<s>
SQL	B-Operating_System
CE	I-Operating_System
runtime	O
has	O
support	O
for	O
DataDirectories	O
.	O
</s>
<s>
Applications	O
using	O
an	O
SQL	B-Operating_System
CE	I-Operating_System
database	O
need	O
not	O
specify	O
the	O
entire	O
path	O
to	O
an	O
.sdf	O
file	O
in	O
the	O
ADO.NET	B-Device
connection	O
string	O
,	O
rather	O
it	O
can	O
be	O
specified	O
as	O
|DataDirectory|	O
\xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx1.sdf,	O
defining	O
the	O
data	O
directory	O
(	O
where	O
the	O
.sdf	O
database	O
file	O
resides	O
)	O
being	O
defined	O
in	O
the	O
assembly	O
manifest	O
for	O
the	O
application	O
.	O
</s>
<s>
SQL	B-Device
Server	I-Device
Management	I-Device
Studio	I-Device
2005	O
can	O
read	O
and	O
modify	O
CE	O
3.0	O
and	O
3.1	O
database	O
files	O
(	O
with	O
the	O
latest	O
service	O
pack	O
)	O
,	O
but	O
SQL	B-Device
Server	I-Device
Management	I-Device
Studio	I-Device
2008	O
(	O
or	O
later	O
)	O
is	O
required	O
to	O
read	O
version	O
3.5	O
files	O
.	O
</s>
<s>
Microsoft	B-Application
Visual	I-Application
Studio	I-Application
Express	O
2008	O
SP1	O
can	O
create	O
,	O
modify	O
,	O
and	O
query	O
CE	O
3.5	O
SP1	O
database	O
files	O
.	O
</s>
<s>
SQL	B-Device
Server	I-Device
Management	I-Device
Studio	I-Device
cannot	O
read	O
CE	O
4.0	O
files	O
.	O
</s>
<s>
Visual	B-Application
Studio	I-Application
2010	O
SP1	O
can	O
handle	O
CE	O
4.0	O
database	O
files	O
.	O
</s>
<s>
The	O
.sdf	O
(	O
"	O
Sqlce	B-Operating_System
Database	O
File	O
"	O
)	O
naming	O
convention	O
is	O
optional	O
,	O
and	O
any	O
extension	O
can	O
be	O
used	O
.	O
</s>
<s>
In	O
February	O
2013	O
,	O
Microsoft	O
announced	O
that	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
Edition	I-Operating_System
had	O
been	O
deprecated	O
.	O
</s>
<s>
Although	O
no	O
new	O
versions	O
or	O
updates	O
are	O
planned	O
,	O
Microsoft	O
will	O
continue	O
to	O
support	O
SQL	O
Compact	B-General_Concept
through	O
their	O
standard	O
lifecycle	O
support	O
policy	O
.	O
</s>
<s>
Extended	O
support	O
for	O
SQL	B-Operating_System
Server	I-Operating_System
Compact	I-Operating_System
4.0	O
ended	O
on	O
July	O
13	O
,	O
2021	O
.	O
</s>
