<s>
Microsoft	B-Library
Data	I-Library
Access	I-Library
Components	I-Library
(	O
MDAC	O
;	O
also	O
known	O
as	O
Windows	B-Application
DAC	O
)	O
is	O
a	O
framework	B-Architecture
of	O
interrelated	O
Microsoft	O
technologies	O
that	O
allows	O
programmers	O
a	O
uniform	O
and	O
comprehensive	O
way	O
of	O
developing	O
applications	O
that	O
can	O
access	O
almost	O
any	O
data	O
store	O
.	O
</s>
<s>
Its	O
components	O
include	O
:	O
ActiveX	B-Library
Data	I-Library
Objects	I-Library
(	O
ADO	B-Library
)	O
,	O
OLE	B-Language
DB	I-Language
,	O
and	O
Open	B-Application
Database	I-Application
Connectivity	I-Application
(	O
ODBC	B-Application
)	O
.	O
</s>
<s>
There	O
have	O
been	O
several	O
deprecated	O
components	O
as	O
well	O
,	O
such	O
as	O
the	O
Jet	B-Application
Database	I-Application
Engine	I-Application
,	O
MSDASQL	O
(	O
the	O
OLE	B-Language
DB	I-Language
provider	I-Language
for	O
ODBC	B-Application
)	O
,	O
and	O
Remote	B-Library
Data	I-Library
Services	I-Library
(	O
RDS	O
)	O
.	O
</s>
<s>
Some	O
components	O
have	O
also	O
become	O
obsolete	O
,	O
such	O
as	O
the	O
former	O
Data	B-Library
Access	I-Library
Objects	I-Library
API	B-Application
and	O
Remote	B-Device
Data	I-Device
Objects	I-Device
.	O
</s>
<s>
Eventually	O
,	O
later	O
versions	O
were	O
integrated	O
with	O
Microsoft	B-Application
Windows	I-Application
and	O
Internet	B-Application
Explorer	I-Application
,	O
and	O
in	O
MDAC	O
2.8	O
SP1	O
they	O
ceased	O
offering	O
MDAC	O
as	O
a	O
redistributable	O
package	O
.	O
</s>
<s>
MDAC	O
is	O
now	O
known	O
as	O
Windows	B-Application
DAC	O
in	O
Windows	B-Application
Vista	I-Application
.	O
</s>
<s>
The	O
latest	O
version	O
of	O
MDAC	O
(	O
2.8	O
)	O
consists	O
of	O
several	O
interacting	O
components	O
,	O
all	O
of	O
which	O
are	O
Windows	B-Application
specific	O
except	O
for	O
ODBC	B-Application
(	O
which	O
is	O
available	O
on	O
several	O
platforms	O
)	O
.	O
</s>
<s>
MDAC	O
architecture	O
may	O
be	O
viewed	O
as	O
three	O
layers	O
:	O
a	O
programming	B-Application
interface	I-Application
layer	O
,	O
consisting	O
of	O
ADO	B-Library
and	O
ADO.NET	B-Device
,	O
a	O
database	O
access	O
layer	O
developed	O
by	O
database	O
vendors	O
such	O
as	O
Oracle	B-General_Concept
and	O
Microsoft	O
(	O
OLE	B-Language
DB	I-Language
,	O
.NET	O
managed	O
providers	O
and	O
ODBC	B-Application
drivers	O
)	O
,	O
and	O
the	O
database	O
itself	O
.	O
</s>
<s>
These	O
component	O
layers	O
are	O
all	O
made	O
available	O
to	O
applications	O
through	O
the	O
MDAC	O
API	B-Application
.	O
</s>
<s>
The	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
Network	O
Library	O
,	O
a	O
proprietary	O
access	O
method	O
specific	O
to	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
is	O
also	O
included	O
in	O
the	O
MDAC	O
.	O
</s>
<s>
Developers	O
of	O
Windows	B-Application
applications	I-Application
are	O
encouraged	O
to	O
use	O
ADO	B-Library
or	O
ADO.NET	B-Device
for	O
data	O
access	O
,	O
the	O
benefit	O
being	O
that	O
users	O
of	O
the	O
application	O
program	O
are	O
not	O
constrained	O
in	O
their	O
choice	O
of	O
database	O
architecture	O
except	O
that	O
it	O
should	O
be	O
supported	O
by	O
MDAC	O
.	O
</s>
<s>
Naturally	O
,	O
developers	O
still	O
have	O
the	O
choice	O
of	O
writing	O
applications	O
which	O
directly	O
access	O
OLE	B-Language
DB	I-Language
and	O
ODBC	B-Application
.	O
</s>
<s>
The	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
Network	O
Library	O
(	O
also	O
known	O
as	O
Net-Lib	O
)	O
is	O
used	O
by	O
the	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
to	O
read	O
and	O
write	O
data	O
using	O
many	O
different	O
network	O
protocols	O
.	O
</s>
<s>
Though	O
Net-Lib	O
is	O
specific	O
to	O
the	O
SQL	B-Application
Server	I-Application
,	O
Microsoft	O
includes	O
it	O
with	O
MDAC	O
.	O
</s>
<s>
The	O
SQL	B-Application
Server	I-Application
uses	O
the	O
Open	O
Data	O
Services	O
(	O
ODS	O
)	O
library	O
to	O
communicate	O
with	O
Net-Lib	O
,	O
which	O
interfaces	B-Application
directly	O
with	O
the	O
Windows	B-Device
NT	I-Device
operating	O
system	O
line	O
's	O
Win32	B-Library
subsystem	O
.	O
</s>
<s>
The	O
SQL	B-Application
Server	I-Application
Network	O
Library	O
is	O
controlled	O
through	O
the	O
use	O
of	O
a	O
Client	O
Network	O
Utility	O
,	O
which	O
is	O
bundled	O
with	O
the	O
SQL	B-Application
Server	I-Application
.	O
</s>
<s>
Each	O
Net-Lib	O
supported	O
network	O
protocol	O
has	O
a	O
separate	O
driver	B-Application
(	O
not	O
to	O
be	O
confused	O
with	O
a	O
device	B-Application
driver	I-Application
)	O
,	O
and	O
has	O
support	O
for	O
a	O
session	B-Application
layer	I-Application
in	O
its	O
protocol	O
stack	O
.	O
</s>
<s>
The	O
primary	O
Net-Lib	O
consists	O
of	O
a	O
Super	O
Socket	O
Net-Lib	O
and	O
the	O
Shared	B-Operating_System
Memory	I-Operating_System
Net-Lib	O
,	O
while	O
there	O
are	O
numerous	O
secondary	O
Net-Libs	O
,	O
including	O
TCP/IP	B-Protocol
and	O
named	B-Operating_System
pipes	I-Operating_System
network	O
libraries	O
(	O
named	B-Operating_System
pipes	I-Operating_System
are	O
a	O
method	O
of	O
communicating	O
with	O
other	O
processes	O
via	O
a	O
system-persistent	O
pipeline	B-Operating_System
that	O
is	O
given	O
an	O
identity	O
)	O
.	O
</s>
<s>
The	O
Microsoft	O
OLE	B-Language
DB	I-Language
Provider	I-Language
for	O
SQL	B-Application
Server	I-Application
(	O
SQLOLEDB	O
)	O
communicates	O
via	O
primary	O
Net-Libs	O
.	O
</s>
<s>
The	O
Super	O
Socket	O
Net-Lib	O
deals	O
with	O
inter-computer	O
communications	O
and	O
coordinates	O
the	O
secondary	O
Net-Libs	O
though	O
the	O
TCP/IP	B-Protocol
secondary	O
Net-Lib	O
is	O
an	O
exception	O
in	O
that	O
it	O
calls	O
on	O
the	O
Windows	B-Application
Sockets	I-Application
2	I-Application
API	B-Application
directly	O
.	O
</s>
<s>
The	O
Banyan	B-Operating_System
VINES	I-Operating_System
,	O
AppleTalk	B-Application
,	O
ServerNet	B-General_Concept
,	O
IPX/SPX	B-Protocol
,	O
Giganet	O
,	O
and	O
RPC	B-Operating_System
Net-Libs	O
were	O
dropped	O
from	O
MDAC	O
2.5	O
onwards	O
.	O
</s>
<s>
The	O
Network	O
Library	O
router	O
had	O
the	O
job	O
of	O
managing	O
all	O
these	O
protocols	O
,	O
however	O
now	O
only	O
the	O
named	B-Operating_System
pipes	I-Operating_System
secondary	O
Net-Lib	O
is	O
managed	O
by	O
the	O
router	O
.	O
</s>
<s>
The	O
Super	O
Socket	O
Net-Lib	O
also	O
handles	O
data	O
encryption	O
via	O
the	O
use	O
of	O
the	O
Windows	B-Application
SSL	B-Protocol
API	B-Application
.	O
</s>
<s>
The	O
Shared	B-Operating_System
Memory	I-Operating_System
Net-Lib	O
,	O
on	O
the	O
other	O
hand	O
,	O
manages	O
connections	O
between	O
multiple	O
instances	O
of	O
SQL	B-Application
Server	I-Application
that	O
exist	O
on	O
one	O
computer	O
.	O
</s>
<s>
It	O
uses	O
a	O
shared	B-Operating_System
memory	I-Operating_System
area	O
to	O
communicate	O
between	O
the	O
processes	O
.	O
</s>
<s>
This	O
is	O
inherently	O
secure	O
;	O
there	O
is	O
no	O
need	O
for	O
data	O
encryption	O
between	O
instances	O
of	O
SQL	B-Application
Server	I-Application
that	O
exist	O
on	O
one	O
computer	O
as	O
the	O
operating	O
system	O
does	O
not	O
allow	O
any	O
other	O
process	O
access	O
to	O
the	O
instances	O
 '	O
area	O
of	O
shared	B-Operating_System
memory	I-Operating_System
.	O
</s>
<s>
This	O
allows	O
Net-Lib	O
to	O
provide	O
an	O
integrated	O
logon	O
authentication	O
mechanism	O
via	O
the	O
use	O
of	O
Windows	B-Application
Authentication	O
.	O
</s>
<s>
Windows	B-Application
Authentication	O
is	O
not	O
supported	O
on	O
Windows	B-Device
98	I-Device
or	O
Windows	B-Device
Me	I-Device
.	O
</s>
<s>
OLE	B-Language
DB	I-Language
(	O
also	O
called	O
OLEDB	B-Language
or	O
OLE-DB	B-Language
)	O
allows	O
MDAC	O
applications	O
access	O
to	O
different	O
types	O
of	O
data	O
stores	O
in	O
a	O
uniform	O
manner	O
.	O
</s>
<s>
The	O
consumers	O
are	O
the	O
applications	O
that	O
need	O
access	O
to	O
the	O
data	O
,	O
and	O
the	O
provider	O
is	O
the	O
software	O
component	O
that	O
exposes	O
an	O
OLE	B-Language
DB	I-Language
interface	B-Application
through	O
the	O
use	O
of	O
the	O
Component	B-Application
Object	I-Application
Model	I-Application
(	O
or	O
COM	O
)	O
.	O
</s>
<s>
OLE	B-Language
DB	I-Language
is	O
the	O
database	O
access	O
interface	B-Application
technology	O
used	O
by	O
MDAC	O
.	O
</s>
<s>
OLE	B-Language
DB	I-Language
providers	I-Language
can	O
be	O
created	O
to	O
access	O
such	O
simple	O
data	O
stores	O
as	O
a	O
text	O
file	O
or	O
spreadsheet	B-Application
,	O
through	O
to	O
such	O
complex	O
databases	O
as	O
Oracle	B-General_Concept
and	O
SQL	B-Application
Server	I-Application
.	O
</s>
<s>
However	O
,	O
because	O
different	O
data	O
store	O
technology	O
can	O
have	O
different	O
capabilities	O
,	O
OLE	B-Language
DB	I-Language
providers	I-Language
may	O
not	O
implement	O
every	O
possible	O
interface	B-Application
available	O
.	O
</s>
<s>
The	O
capabilities	O
that	O
are	O
available	O
are	O
implemented	O
through	O
the	O
use	O
of	O
COM	B-Application
objects	I-Application
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
will	O
map	O
the	O
data	O
store	O
technology	O
's	O
functionality	O
to	O
a	O
particular	O
COM	O
interface	B-Application
.	O
</s>
<s>
Microsoft	O
calls	O
the	O
availability	O
of	O
an	O
interface	B-Application
to	O
be	O
"	O
provider-specific	O
"	O
as	O
it	O
may	O
not	O
be	O
applicable	O
depending	O
on	O
the	O
database	O
technology	O
involved	O
.	O
</s>
<s>
The	O
Microsoft	O
OLE	B-Language
DB	I-Language
Provider	I-Language
for	O
SQL	B-Application
Server	I-Application
(	O
SQLOLEDB	O
)	O
is	O
the	O
OLE	B-Language
DB	I-Language
provider	I-Language
that	O
Microsoft	O
provides	O
for	O
the	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
from	O
version	O
6.5	O
upwards	O
.	O
</s>
<s>
Universal	O
data	O
link	O
files	O
(	O
or	O
'	O
.udl	O
files	O
 '	O
)	O
provide	O
a	O
common	O
user	O
interface	B-Application
for	O
specifying	O
connection	O
attributes	O
.	O
</s>
<s>
Additionally	O
,	O
the	O
dialog	O
box	O
specifies	O
a	O
number	O
of	O
alternate	O
OLE	B-Language
DB	I-Language
data	O
providers	O
for	O
a	O
variety	O
of	O
target	O
applications	O
.	O
</s>
<s>
Open	B-Application
Database	I-Application
Connectivity	I-Application
(	O
ODBC	B-Application
)	O
is	O
a	O
native	O
interface	B-Application
that	O
is	O
accessed	O
through	O
a	O
programming	O
language	O
(	O
usually	O
C	B-Language
)	O
that	O
can	O
make	O
calls	O
into	O
a	O
native	B-Library
library	I-Library
.	O
</s>
<s>
In	O
MDAC	O
this	O
interface	B-Application
is	O
defined	O
as	O
a	O
DLL	O
.	O
</s>
<s>
A	O
separate	O
module	O
or	O
driver	B-Application
is	O
needed	O
for	O
each	O
database	O
that	O
must	O
be	O
accessed	O
.	O
</s>
<s>
The	O
functions	O
in	O
the	O
ODBC	B-Application
API	B-Application
are	O
implemented	O
by	O
these	O
DBMS-specific	O
drivers	O
.	O
</s>
<s>
The	O
driver	B-Application
that	O
Microsoft	O
provides	O
in	O
MDAC	O
is	O
called	O
the	O
SQL	B-Application
Server	I-Application
ODBC	B-Application
Driver	B-Application
(	O
SQLODBC	O
)	O
,	O
and	O
(	O
as	O
the	O
name	O
implies	O
)	O
is	O
designed	O
for	O
Microsoft	O
's	O
SQL	B-Application
Server	I-Application
.	O
</s>
<s>
It	O
supports	O
SQL	B-Application
Server	I-Application
v6.5	O
and	O
upwards	O
.	O
</s>
<s>
ODBC	B-Application
allows	O
programs	O
to	O
use	O
SQL	B-Language
requests	O
that	O
will	O
access	O
databases	O
without	O
having	O
to	O
know	O
the	O
proprietary	O
interfaces	B-Application
to	O
the	O
databases	O
.	O
</s>
<s>
It	O
handles	O
the	O
SQL	B-Language
request	O
and	O
converts	O
it	O
into	O
a	O
request	O
that	O
the	O
individual	O
database	O
system	O
understands	O
.	O
</s>
<s>
According	O
to	O
Microsoft	O
,	O
"	O
After	O
SQL	B-Application
Server	I-Application
2012	O
,	O
the	O
ODBC	B-Application
driver	B-Application
will	O
be	O
updated	O
for	O
the	O
most	O
recent	O
server	O
features	O
,	O
including	O
Microsoft	B-Application
Windows	I-Application
Azure	O
SQL	B-Language
Database	I-Language
,	O
and	O
released	O
as	O
the	O
Microsoft	O
ODBC	B-Application
Driver	B-Application
for	O
SQL	O
Server.	O
"	O
</s>
<s>
ActiveX	B-Library
Data	I-Library
Objects	I-Library
(	O
ADO	B-Library
)	O
is	O
a	O
high-level	O
programming	B-Application
interface	I-Application
to	O
OLE	B-Language
DB	I-Language
.	O
</s>
<s>
It	O
uses	O
a	O
hierarchical	O
object	B-Language
model	O
to	O
allow	O
applications	O
to	O
programmatically	O
create	B-General_Concept
,	I-General_Concept
retrieve	I-General_Concept
,	I-General_Concept
update	I-General_Concept
and	I-General_Concept
delete	I-General_Concept
data	O
from	O
sources	O
supported	O
by	O
OLE	B-Language
DB	I-Language
.	O
</s>
<s>
ADO	B-Library
consists	O
of	O
a	O
series	O
of	O
hierarchical	O
COM-based	O
objects	O
and	O
collections	B-Application
,	O
an	O
object	B-Language
that	O
acts	O
as	O
a	O
container	B-Application
of	O
many	O
other	O
objects	O
.	O
</s>
<s>
A	O
programmer	O
can	O
directly	O
access	O
ADO	B-Library
objects	O
to	O
manipulate	O
data	O
,	O
or	O
can	O
send	O
an	O
SQL	B-Language
query	O
to	O
the	O
database	O
via	O
several	O
ADO	B-Library
mechanisms	O
.	O
</s>
<s>
ADO	B-Library
is	O
made	O
up	O
of	O
nine	O
objects	O
and	O
four	O
collections	B-Application
.	O
</s>
<s>
The	O
collections	B-Application
are	O
:	O
</s>
<s>
The	O
collection	O
can	O
be	O
used	O
in	O
either	O
a	O
Recordset	B-Application
object	B-Language
or	O
in	O
a	O
Record	B-Operating_System
object	B-Language
.	O
</s>
<s>
In	O
a	O
Recordset	B-Application
object	B-Language
,	O
each	O
of	O
the	O
Field	O
objects	O
that	O
make	O
up	O
the	O
Fields	O
collection	O
corresponds	O
to	O
a	O
column	B-Application
in	O
that	O
Recordset	B-Application
object	B-Language
.	O
</s>
<s>
In	O
a	O
Record	B-Operating_System
object	B-Language
,	O
a	O
Field	O
can	O
be	O
an	O
absolute	O
or	O
relative	O
URL	O
that	O
points	O
into	O
a	O
tree-structured	O
namespace	O
(	O
used	O
for	O
semi-structured	B-Application
data	I-Application
providers	O
like	O
the	O
Microsoft	O
OLE	B-Language
DB	I-Language
Provider	I-Language
for	O
Internet	O
Publishing	O
)	O
or	O
as	O
a	O
reference	O
to	O
the	O
default	O
Stream	O
object	B-Language
associated	O
with	O
that	O
Record	B-Operating_System
object	B-Language
.	O
</s>
<s>
Properties	O
:	O
An	O
object	B-Language
can	O
have	O
more	O
than	O
one	O
Property	O
object	B-Language
,	O
which	O
are	O
contained	O
in	O
the	O
object	B-Language
's	O
Properties	O
collection	O
.	O
</s>
<s>
Errors	O
:	O
All	O
provider	O
created	O
errors	O
are	O
passed	O
to	O
a	O
collection	O
of	O
Error	O
objects	O
,	O
while	O
the	O
Errors	O
collection	O
itself	O
is	O
contained	O
in	O
a	O
Connection	O
object	B-Language
.	O
</s>
<s>
When	O
an	O
ADO	B-Library
operation	O
creates	O
an	O
error	O
,	O
the	O
collection	O
is	O
cleared	O
and	O
a	O
new	O
group	O
of	O
Error	O
objects	O
are	O
created	O
in	O
the	O
collection	O
.	O
</s>
<s>
Connection	O
:	O
The	O
connection	O
object	B-Language
is	O
ADO	B-Library
's	O
connection	O
to	O
a	O
data	O
store	O
via	O
OLE	B-Language
DB	I-Language
.	O
</s>
<s>
The	O
connection	O
object	B-Language
stores	O
information	O
about	O
the	O
session	O
and	O
provides	O
methods	O
of	O
connecting	O
to	O
the	O
data	O
store	O
.	O
</s>
<s>
As	O
some	O
data	O
stores	O
have	O
different	O
methods	O
of	O
establishing	O
a	O
connection	O
,	O
some	O
methods	O
may	O
not	O
be	O
supported	O
in	O
the	O
connection	O
object	B-Language
for	O
particular	O
OLE	B-Language
DB	I-Language
providers	I-Language
.	O
</s>
<s>
A	O
connection	O
object	B-Language
connects	O
to	O
the	O
data	O
store	O
using	O
its	O
'	O
Open	O
 '	O
method	O
with	O
a	O
connection	O
string	O
which	O
specifies	O
the	O
connection	O
as	O
a	O
list	O
of	O
key	O
value	O
pairs	O
(	O
for	O
example	O
:	O
"	O
Provider='SQLOLEDB'	O
;D	O
ata	O
Source='TheSqlServer'	O
;	O
Initial	O
Catalog='Northwind'	O
;	O
Integrated	O
Security='SSPI'	O
;	O
"	O
)	O
.	O
</s>
<s>
The	O
start	O
of	O
which	O
must	O
identify	O
the	O
type	O
of	O
data	O
store	O
connection	O
that	O
the	O
connection	O
object	B-Language
requires	O
.	O
</s>
<s>
Command	O
:	O
After	O
the	O
connection	O
object	B-Language
establishes	O
a	O
session	O
to	O
the	O
data	O
source	O
,	O
instructions	O
are	O
sent	O
to	O
the	O
data	O
provider	O
via	O
the	O
command	O
object	B-Language
.	O
</s>
<s>
The	O
command	O
object	B-Language
can	O
send	O
SQL	B-Language
queries	O
directly	O
to	O
the	O
provider	O
through	O
the	O
use	O
of	O
the	O
CommandText	O
property	O
,	O
send	O
a	O
parameterised	O
query	O
or	O
stored	B-General_Concept
procedure	I-General_Concept
through	O
the	O
use	O
of	O
a	O
Parameter	O
object	B-Language
or	O
Parameters	O
collection	O
or	O
run	O
a	O
query	O
and	O
return	O
the	O
results	O
to	O
a	O
dataset	O
object	B-Language
via	O
the	O
Execute	O
method	O
.	O
</s>
<s>
There	O
are	O
several	O
other	O
methods	O
that	O
can	O
be	O
used	O
in	O
the	O
Command	O
object	B-Language
relating	O
to	O
other	O
objects	O
,	O
such	O
as	O
the	O
Stream	O
,	O
RecordSet	B-Application
or	O
Connection	O
objects	O
.	O
</s>
<s>
Recordset	B-Application
:	O
A	O
recordset	B-Application
is	O
a	O
group	O
of	O
records	O
,	O
and	O
can	O
either	O
come	O
from	O
a	O
base	O
table	O
or	O
as	O
the	O
result	O
of	O
a	O
query	O
to	O
the	O
table	O
.	O
</s>
<s>
The	O
RecordSet	B-Application
object	B-Language
contains	O
a	O
Fields	O
collection	O
and	O
a	O
Properties	O
collection	O
.	O
</s>
<s>
The	O
Fields	O
collection	O
is	O
a	O
set	O
of	O
Field	O
objects	O
,	O
which	O
are	O
the	O
corresponding	O
columns	B-Application
in	O
the	O
table	O
.	O
</s>
<s>
The	O
Properties	O
collection	O
is	O
a	O
set	O
of	O
Property	O
objects	O
,	O
which	O
defines	O
a	O
particular	O
functionality	O
of	O
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
.	O
</s>
<s>
The	O
RecordSet	B-Application
has	O
numerous	O
methods	O
and	O
properties	O
for	O
examining	O
the	O
data	O
that	O
exists	O
within	O
it	O
.	O
</s>
<s>
Records	O
can	O
be	O
updated	O
in	O
the	O
recordset	B-Application
by	O
changing	O
the	O
values	O
in	O
the	O
record	B-Operating_System
and	O
then	O
calling	O
on	O
the	O
Update	O
or	O
UpdateBatch	O
method	O
.	O
</s>
<s>
Records	O
are	O
also	O
deleted	O
in	O
the	O
recordset	B-Application
with	O
the	O
Delete	O
method	O
and	O
then	O
by	O
calling	O
on	O
the	O
Update	O
method	O
.	O
</s>
<s>
However	O
,	O
if	O
for	O
some	O
reason	O
the	O
deletion	O
cannot	O
occur	O
,	O
such	O
as	O
because	O
of	O
violations	O
in	O
referential	B-General_Concept
integrity	I-General_Concept
,	O
then	O
the	O
recordset	B-Application
will	O
remain	O
in	O
edit	O
mode	O
after	O
the	O
call	O
to	O
the	O
Update	O
method	O
.	O
</s>
<s>
Additionally	O
,	O
ADO	B-Library
can	O
roll	B-Application
back	I-Application
transactions	B-General_Concept
(	O
if	O
this	O
is	O
supported	O
)	O
and	O
cancel	O
batch	O
updates	O
.	O
</s>
<s>
Recordsets	B-Application
can	O
also	O
be	O
updated	O
in	O
one	O
of	O
three	O
ways	O
:	O
via	O
an	O
immediate	O
update	O
,	O
via	O
a	O
batch	O
update	O
,	O
or	O
through	O
the	O
use	O
of	O
transactions	B-General_Concept
:	O
</s>
<s>
Immediate	O
:	O
The	O
recordset	B-Application
is	O
locked	O
using	O
the	O
adLockOptimistic	O
or	O
adLockPessimistic	O
lock	O
.	O
</s>
<s>
The	O
data	O
are	O
updated	O
at	O
the	O
data	O
source	O
after	O
the	O
record	B-Operating_System
is	O
changed	O
and	O
the	O
Update	O
method	O
is	O
called	O
.	O
</s>
<s>
Batch	O
:	O
The	O
recordset	B-Application
is	O
locked	O
using	O
adLockBatchOptimistic	O
and	O
each	O
time	O
Update	O
is	O
called	O
the	O
data	O
are	O
updated	O
in	O
a	O
temporary	O
buffer	O
.	O
</s>
<s>
Transaction	O
:	O
If	O
the	O
OLE	B-Language
DB	I-Language
provider	I-Language
allows	O
it	O
,	O
transactions	B-General_Concept
can	O
be	O
used	O
.	O
</s>
<s>
Record	B-Operating_System
:	O
This	O
object	B-Language
represents	O
one	O
record	B-Operating_System
in	O
the	O
database	O
,	O
and	O
contains	O
a	O
fields	O
collection	O
.	O
</s>
<s>
A	O
RecordSet	B-Application
consists	O
of	O
a	O
collection	O
of	O
Record	B-Operating_System
objects	O
.	O
</s>
<s>
Stream	O
:	O
A	O
stream	O
,	O
mainly	O
used	O
in	O
a	O
RecordSet	B-Application
object	B-Language
,	O
is	O
a	O
means	O
of	O
reading	O
and	O
writing	O
a	O
stream	O
of	O
bytes	O
.	O
</s>
<s>
It	O
is	O
mostly	O
used	O
to	O
save	O
a	O
recordset	B-Application
in	O
an	O
XML	B-Protocol
format	O
,	O
to	O
send	O
commands	O
to	O
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
as	O
an	O
alternative	O
to	O
the	O
CommandText	O
object	B-Language
and	O
to	O
contain	O
the	O
contents	O
of	O
a	O
binary	O
or	O
text	O
file	O
.	O
</s>
<s>
Parameter	O
:	O
A	O
parameter	O
is	O
a	O
means	O
of	O
altering	O
the	O
behaviour	O
of	O
a	O
common	O
piece	O
of	O
functionality	O
,	O
for	O
instance	O
a	O
stored	B-General_Concept
procedure	I-General_Concept
might	O
have	O
different	O
parameters	O
passed	O
to	O
it	O
depending	O
on	O
what	O
needs	O
to	O
be	O
done	O
;	O
these	O
are	O
called	O
parameterised	O
commands	O
.	O
</s>
<s>
Field	O
:	O
Each	O
Record	B-Operating_System
object	B-Language
contains	O
many	O
fields	O
,	O
and	O
a	O
RecordSet	B-Application
object	B-Language
has	O
a	O
corresponding	O
Field	O
object	B-Language
also	O
.	O
</s>
<s>
The	O
RecordSet	B-Application
object	B-Language
's	O
Field	O
object	B-Language
corresponds	O
to	O
a	O
column	B-Application
in	O
the	O
database	O
table	O
that	O
it	O
references	O
.	O
</s>
<s>
Property	O
:	O
This	O
object	B-Language
is	O
specific	O
to	O
the	O
OLE	B-Language
DB	I-Language
provider	I-Language
and	O
defines	O
an	O
ability	O
that	O
the	O
provider	O
has	O
implemented	O
.	O
</s>
<s>
Error	O
:	O
When	O
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
error	O
occurs	O
during	O
the	O
use	O
of	O
ADO	B-Library
,	O
an	O
Error	O
object	B-Language
will	O
be	O
created	O
in	O
the	O
Errors	O
collection	O
.	O
</s>
<s>
Other	O
errors	O
do	O
not	O
go	O
into	O
an	O
Error	O
object	B-Language
,	O
however	O
.	O
</s>
<s>
For	O
instance	O
,	O
any	O
errors	O
that	O
occur	O
when	O
manipulating	O
data	O
in	O
a	O
RecordSet	B-Application
or	O
Field	O
object	B-Language
are	O
stored	O
in	O
a	O
Status	O
property	O
.	O
</s>
<s>
ADO.NET	B-Device
is	O
the	O
latest	O
version	O
of	O
ADO	B-Library
(	O
after	O
ADO	B-Library
2.8	O
,	O
now	O
often	O
referred	O
to	O
as	O
ADO	B-Library
Classic	O
)	O
and	O
is	O
part	O
of	O
the	O
MDAC	O
2.8	O
stack	O
alongside	O
classic	O
ADO	B-Library
.	O
</s>
<s>
Though	O
sometimes	O
seen	O
as	O
an	O
evolutionary	O
step	O
up	O
from	O
ADO	B-Library
,	O
some	O
fundamental	O
structural	O
changes	O
were	O
made	O
by	O
Microsoft	O
.	O
</s>
<s>
ADO.NET	B-Device
runs	O
through	O
a	O
.NET	O
Managed	O
Provider	O
,	O
a	O
modified	O
version	O
of	O
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
specifically	O
designed	O
for	O
.NET	O
.	O
</s>
<s>
The	O
object	B-Language
structure	O
is	O
no	O
longer	O
built	O
around	O
a	O
Recordset	B-Application
object	B-Language
.	O
</s>
<s>
Instead	O
a	O
Dataset	O
object	B-Language
is	O
used	O
to	O
contain	O
data	O
gathered	O
from	O
multiple	O
sources	O
.	O
</s>
<s>
Unlike	O
the	O
old	O
ADO	B-Library
Recordset	B-Application
,	O
the	O
Dataset	O
's	O
design	O
promotes	O
the	O
use	O
of	O
disconnected	O
data	O
.	O
</s>
<s>
Conceptually	O
,	O
a	O
Dataset	O
object	B-Language
can	O
be	O
seen	O
as	O
a	O
small	O
in-memory	O
relational	O
database	O
in	O
its	O
own	O
right	O
that	O
allows	O
for	O
manipulation	O
of	O
data	O
in	O
any	O
direction	O
.	O
</s>
<s>
In	O
order	O
to	O
propagate	O
changes	O
back	O
into	O
the	O
database	O
,	O
a	O
DataAdapter	B-Device
object	B-Language
is	O
used	O
that	O
transfers	O
data	O
from	O
between	O
the	O
data	O
source	O
and	O
the	O
DataSet	O
object	B-Language
.	O
</s>
<s>
Cursors	B-Language
were	O
also	O
deprecated	O
in	O
ADO.NET	B-Device
,	O
being	O
replaced	O
with	O
a	O
DataReader	B-Language
object	B-Language
,	O
which	O
is	O
used	O
to	O
efficiently	O
process	O
a	O
large	O
list	O
of	O
results	O
one	O
record	B-Operating_System
at	O
a	O
time	O
without	O
storing	O
them	O
.	O
</s>
<s>
MDAC	O
is	O
a	O
continually	O
evolving	O
component	O
framework	B-Architecture
.	O
</s>
<s>
As	O
such	O
,	O
there	O
have	O
been	O
several	O
components	O
that	O
were	O
previously	O
part	O
of	O
it	O
but	O
have	O
since	O
been	O
deprecated	O
or	O
removed	O
entirely	O
from	O
the	O
framework	B-Architecture
.	O
</s>
<s>
Jet	B-Application
stands	O
for	O
Joint	B-Application
Engine	I-Application
Technology	I-Application
and	O
was	O
a	O
database	B-General_Concept
engine	I-General_Concept
used	O
for	O
Microsoft	B-Application
Access	I-Application
,	O
Microsoft	B-Operating_System
Exchange	I-Operating_System
Server	I-Operating_System
and	O
Visual	B-Language
Basic	I-Language
.	O
</s>
<s>
Jet	B-Application
was	O
part	O
of	O
a	O
Relational	B-Application
Database	I-Application
Management	I-Application
System	I-Application
(	O
RDBMS	O
)	O
and	O
offered	O
a	O
single	O
interface	B-Application
that	O
other	O
software	O
could	O
use	O
to	O
access	O
Microsoft	O
databases	O
.	O
</s>
<s>
Jet	B-Application
also	O
provided	O
support	O
for	O
security	O
,	O
referential	B-General_Concept
integrity	I-General_Concept
,	O
transaction	B-General_Concept
processing	I-General_Concept
,	O
indexing	O
,	O
record	B-Operating_System
and	O
page	O
locking	O
,	O
and	O
data	O
replication	O
.	O
</s>
<s>
In	O
later	O
versions	O
of	O
Jet	B-Application
,	O
the	O
engine	O
was	O
extended	O
to	O
run	O
SQL	B-Language
queries	O
,	O
store	O
character	O
data	O
in	O
Unicode	O
format	O
,	O
create	O
views	B-Language
,	O
and	O
allowed	O
bi-directional	O
replication	O
with	O
the	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
.	O
</s>
<s>
It	O
was	O
superseded	O
by	O
MSDE	B-Application
which	O
was	O
superseded	O
SQL	B-Application
Server	I-Application
Express	I-Application
.	O
</s>
<s>
There	O
were	O
three	O
modules	O
to	O
Jet	B-Application
.	O
</s>
<s>
One	O
was	O
the	O
Native	O
Jet	B-Application
ISAM	B-Application
Driver	B-Application
,	O
a	O
Jet	B-Application
dynamic	O
link	O
library	O
(	O
DLL	O
)	O
that	O
could	O
directly	O
manipulate	O
Microsoft	B-Application
Access	I-Application
database	O
files	O
(	O
MDB	O
)	O
,	O
which	O
was	O
a	O
modified	O
form	O
of	O
an	O
Indexed	B-Application
Sequential	I-Application
Access	I-Application
Method	I-Application
(	O
ISAM	B-Application
)	O
database	O
.	O
</s>
<s>
Another	O
one	O
of	O
the	O
modules	O
were	O
the	O
ISAM	B-Application
Drivers	O
,	O
DLLs	O
that	O
allowed	O
access	O
to	O
ISAM	B-Application
databases	O
,	O
among	O
them	O
being	O
Xbase	B-Language
,	O
Paradox	B-Application
,	O
Btrieve	B-Application
and	O
FoxPro	B-Application
files	O
.	O
</s>
<s>
The	O
final	O
module	O
was	O
the	O
Data	B-Library
Access	I-Library
Objects	I-Library
(	O
DAO	B-Library
)	O
DLL	O
,	O
DAO	B-Library
allowed	O
programmers	O
access	O
to	O
the	O
Jet	B-Application
engine	O
.	O
</s>
<s>
It	O
was	O
basically	O
an	O
object-oriented	B-Language
data	O
language	O
used	O
by	O
Access	O
Basic	O
and	O
Visual	B-Language
Basic	I-Language
application	O
developers	O
to	O
access	O
Jet	B-Application
.	O
</s>
<s>
The	O
Microsoft	O
OLE	B-Language
DB	I-Language
Provider	I-Language
for	O
ODBC	B-Application
,	O
or	O
MSDASQL	O
,	O
was	O
an	O
OLE	B-Language
DB	I-Language
provider	I-Language
for	O
allowing	O
ActiveX	B-Library
Data	I-Library
Objects	I-Library
access	O
to	O
databases	O
via	O
any	O
ODBC	B-Application
driver	B-Application
.	O
</s>
<s>
and	O
Internet	O
Publishing	O
)	O
,	O
however	O
unless	O
otherwise	O
directed	O
,	O
ADO	B-Library
defaulted	O
to	O
using	O
MSDASQL	O
as	O
the	O
default	O
provider	O
.	O
</s>
<s>
After	O
MDAC	O
2.5	O
both	O
the	O
Oracle	B-General_Concept
ODBC	B-Application
driver	B-Application
and	O
MSDASQL	O
supported	O
Oracle	B-General_Concept
7	O
and	O
partially	O
supported	O
Oracle	B-General_Concept
8i	O
.	O
</s>
<s>
and	O
the	O
Microsoft	O
Oracle	B-General_Concept
ODBC	B-Application
driver	B-Application
was	O
later	O
superseded	O
by	O
a	O
.NET	O
Managed	O
Oracle	B-General_Concept
Provider	O
,	O
which	O
supported	O
Oracle	B-General_Concept
9i	O
.	O
</s>
<s>
However	O
,	O
Windows	B-Device
Server	I-Device
2008	I-Device
and	O
Windows	B-Application
Vista	I-Application
SP1	O
ship	O
with	O
a	O
64-bit	B-Device
version	O
of	O
MSDASQL	O
.	O
</s>
<s>
Remote	B-Library
Data	I-Library
Services	I-Library
(	O
RDS	O
)	O
allowed	O
the	O
retrieval	O
of	O
a	O
set	O
of	O
data	O
from	O
the	O
server	O
,	O
which	O
the	O
client	O
then	O
altered	O
in	O
some	O
way	O
and	O
then	O
sent	O
back	O
to	O
the	O
server	O
for	O
further	O
processing	O
.	O
</s>
<s>
With	O
the	O
popular	O
adoption	O
of	O
Transact-SQL	B-Language
,	O
which	O
extends	O
SQL	B-Language
with	O
such	O
programming	O
constructs	O
as	O
loops	O
and	O
conditional	O
statements	O
,	O
this	O
became	O
less	O
necessary	O
and	O
it	O
was	O
eventually	O
deprecated	O
in	O
MDAC	O
2.7	O
.	O
</s>
<s>
Microsoft	O
produced	O
SOAP	B-Application
Toolkit	O
2.0	O
,	O
which	O
allows	O
clients	O
to	O
do	O
this	O
via	O
an	O
open	O
XML-based	O
standard	O
.	O
</s>
<s>
SQLXML	O
was	O
designed	O
for	O
SQL	B-Application
Server	I-Application
2000	O
,	O
but	O
was	O
deprecated	O
with	O
MDAC	O
2.6	O
.	O
</s>
<s>
It	O
allowed	O
Microsoft	O
's	O
relational	O
database	O
to	O
be	O
viewed	O
by	O
XPath	B-Language
and	O
allowed	O
data	O
to	O
viewable	O
as	O
an	O
XML	B-Protocol
file	O
.	O
</s>
<s>
It	O
has	O
not	O
actually	O
been	O
deprecated	O
but	O
has	O
been	O
removed	O
from	O
later	O
versions	O
of	O
MDAC	O
,	O
though	O
Microsoft	O
does	O
provide	O
it	O
as	O
a	O
downloadable	O
component	O
and	O
will	O
support	O
it	O
on	O
their	O
64-bit	B-Device
operating	O
systems	O
.	O
</s>
<s>
DAO	B-Library
:	O
DAO	B-Library
,	O
or	O
Data	B-Library
Access	I-Library
Objects	I-Library
were	O
an	O
object	B-Language
oriented	I-Language
interface	B-Application
created	O
by	O
Microsoft	O
which	O
allowed	O
early	O
versions	O
of	O
Microsoft	B-Application
Access	I-Application
and	O
Visual	B-Language
Basic	I-Language
to	O
access	O
the	O
Jet	B-Application
Database	I-Application
Engine	I-Application
.	O
</s>
<s>
Later	O
(	O
in	O
version	O
3.5	O
)	O
it	O
was	O
able	O
to	O
bypass	O
the	O
Jet	B-Application
engine	O
altogether	O
and	O
directly	O
access	O
ODBC	B-Application
data	O
sources	O
.	O
</s>
<s>
RDO	O
:	O
Remote	B-Device
Data	I-Device
Objects	I-Device
,	O
or	O
RDO	O
,	O
was	O
a	O
Microsoft	O
technology	O
that	O
allowed	O
for	O
the	O
creation	O
of	O
interfaces	B-Application
that	O
directly	O
called	O
on	O
ODBC	B-Application
.	O
</s>
<s>
DB-Library	O
:	O
a	O
C-based	O
API	B-Application
that	O
allowed	O
an	O
application	O
to	O
interact	O
with	O
SQL	B-Application
Server	I-Application
.	O
</s>
<s>
It	O
will	O
not	O
be	O
supported	O
on	O
any	O
product	O
after	O
SQL	B-Application
Server	I-Application
2000	O
,	O
and	O
no	O
features	O
were	O
added	O
after	O
SQL	B-Application
Server	I-Application
6.5	O
.	O
</s>
<s>
The	O
MDAC	O
1.0	O
stack	O
consisted	O
of	O
ODBC	B-Application
3.0	O
,	O
OLE	B-Language
DB	I-Language
1.1	O
,	O
ADO	B-Library
1.0	O
,	O
and	O
the	O
Advanced	B-Library
Data	I-Library
Connector	I-Library
(	O
ADC	O
)	O
1.0	O
which	O
according	O
to	O
Microsoft	O
was	O
the	O
precursor	O
to	O
the	O
Remote	B-Library
Data	I-Library
Service	I-Library
of	O
MDAC	O
1.5	O
.	O
</s>
<s>
It	O
also	O
included	O
ODBC	B-Application
drivers	O
for	O
Access/Jet	O
,	O
SQL	B-Application
Server	I-Application
and	O
Oracle	B-General_Concept
databases	I-General_Concept
.	O
</s>
<s>
MDAC	O
1.0	O
was	O
released	O
via	O
several	O
mechanisms	O
:	O
the	O
Advanced	B-Library
Data	I-Library
Connector	I-Library
shipped	O
with	O
Internet	B-Application
Information	I-Application
Server	I-Application
(	O
IIS	O
)	O
3.0	O
and	O
as	O
a	O
downloadable	O
cab	O
file	O
;	O
OLE	B-Language
DB	I-Language
1.1	O
and	O
ADO	B-Library
1.0	O
shipped	O
with	O
the	O
OLE	B-Language
DB	I-Language
1.1	O
SDK	O
,	O
which	O
came	O
with	O
Visual	B-Application
Studio	I-Application
97	O
and	O
was	O
also	O
downloadable	O
.	O
</s>
<s>
MDAC	O
1.0	O
came	O
with	O
Active	O
Server	O
Pages	O
,	O
that	O
itself	O
came	O
in	O
IIS	O
3.0	O
,	O
and	O
also	O
came	O
with	O
Visual	B-Application
InterDev	I-Application
1.0	O
.	O
</s>
<s>
It	O
was	O
released	O
with	O
Microsoft	B-Application
Internet	I-Application
Explorer	I-Application
4.0	O
,	O
the	O
Internet	O
Client	O
SDK	O
4.0	O
and	O
through	O
a	O
CD-ROM	O
given	O
out	O
at	O
the	O
1997	O
Professional	O
Developers	O
Conference	O
(	O
PDC	O
)	O
.	O
</s>
<s>
MDAC	O
1.5	O
(	O
initial	O
release	O
)	O
:	O
included	O
with	O
Internet	B-Application
Explorer	I-Application
4.0	O
and	O
the	O
Internet	O
Client	O
SDK	O
.	O
</s>
<s>
MDAC	O
1.5c	O
:	O
fixed	O
issues	O
with	O
ADO	B-Library
threading	O
and	O
ODBC	B-Application
Connection	O
Pooling	O
and	O
was	O
distributed	O
via	O
the	O
Microsoft	O
website	O
.	O
</s>
<s>
It	O
only	O
came	O
with	O
the	O
ADO/MDAC	O
runtime	O
components	O
.	O
</s>
<s>
MDAC	O
1.5d	O
:	O
came	O
included	O
with	O
Windows	B-Device
98	I-Device
and	O
Internet	B-Application
Explorer	I-Application
4.01	O
service	O
pack	O
1	O
.	O
</s>
<s>
Remote	B-Library
Data	I-Library
Service	I-Library
1.5	O
,	O
which	O
superseded	O
the	O
Advanced	B-Library
Data	I-Library
Connector	I-Library
.	O
</s>
<s>
This	O
allowed	O
the	O
attacker	O
to	O
use	O
MDAC	O
to	O
tunnel	O
SQL	B-Language
and	O
other	O
ODBC	B-Application
data	O
requests	O
through	O
the	O
public	O
connection	O
to	O
a	O
private	O
back-end	O
network	O
when	O
on	O
a	O
multi-homed	B-Protocol
Internet-connected	O
IIS	O
system	O
.	O
</s>
<s>
MDAC	O
1.5	O
was	O
the	O
last	O
data	O
access	O
component	O
release	O
supported	O
under	O
Windows	B-Device
NT	I-Device
3.51	O
SP5	O
.	O
</s>
<s>
MDAC	O
2.0	O
was	O
distributed	O
with	O
the	O
Data	O
Access	O
2.0	O
SDK	O
and	O
included	O
the	O
contents	O
of	O
MDAC	O
1.5	O
,	O
the	O
ODBC	B-Application
3.5	O
SDK	O
and	O
the	O
OLE	B-Language
DB	I-Language
1.5	O
SDK	O
,	O
and	O
the	O
OLE	B-Language
DB	I-Language
for	O
OLAP	B-Application
Specification	O
.	O
</s>
<s>
It	O
also	O
had	O
included	O
many	O
updates	O
to	O
the	O
core	O
product	O
,	O
including	O
a	O
security	O
feature	O
added	O
to	O
the	O
RDS	O
which	O
prevented	O
it	O
from	O
being	O
used	O
maliciously	O
an	O
IIS	B-Application
server	I-Application
.	O
</s>
<s>
This	O
version	O
came	O
included	O
in	O
Windows	B-Device
NT	I-Device
4.0	I-Device
SP4	O
,	O
and	O
also	O
with	O
Visual	B-Application
Studio	I-Application
6.0	O
,	O
which	O
came	O
with	O
the	O
full	O
Data	O
Access	O
SDK	O
.	O
</s>
<s>
MDAC	O
2.1	O
was	O
distributed	O
with	O
SQL	B-Application
Server	I-Application
7.0	O
and	O
SQL	B-Application
Server	I-Application
6.5	O
SP5	O
.	O
</s>
<s>
MDAC	O
2.1	O
SP1	O
was	O
distributed	O
with	O
Internet	B-Application
Explorer	I-Application
5	O
and	O
MDAC	O
2.1	O
SP1a	O
(	O
GA	O
)	O
was	O
distributed	O
with	O
Microsoft	B-Application
Office	I-Application
2000	O
,	O
BackOffice	B-General_Concept
4.5	O
and	O
Visual	B-Application
Studio	I-Application
98	O
SP3	O
.	O
</s>
<s>
MDAC	O
2.5	O
was	O
released	O
on	O
February	O
17	O
,	O
2000	O
and	O
distributed	O
with	O
Windows	B-Application
2000	I-Application
,	O
and	O
the	O
MDAC	O
service	O
packs	O
were	O
released	O
in	O
parallel	O
with	O
the	O
Windows	B-Application
2000	I-Application
service	O
packs	O
.	O
</s>
<s>
many	O
Jet	B-Application
drivers	O
.	O
</s>
<s>
When	O
using	O
OLE	B-Language
DB	I-Language
Session	O
Pooling	O
,	O
Microsoft	O
COM+	B-Application
would	O
try	O
to	O
continuously	O
load	O
and	O
unload	O
OLE	B-Language
DB	I-Language
,	O
and	O
a	O
conflict	O
could	O
arise	O
that	O
caused	O
the	O
OLE	B-Language
DB	I-Language
Session	O
Pooling	O
to	O
run	O
at	O
100%	O
CPU	O
usage	O
.	O
</s>
<s>
A	O
security	O
vulnerability	O
also	O
existed	O
(	O
later	O
fixed	O
)	O
whereby	O
an	O
unchecked	O
buffer	O
was	O
found	O
in	O
the	O
SQL	B-Application
Server	I-Application
Driver	B-Application
.	O
</s>
<s>
MDAC	O
2.6	O
was	O
released	O
in	O
September	O
2000	O
and	O
was	O
distributed	O
through	O
the	O
web	O
and	O
with	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
2000	O
MDAC	O
2.6	O
RTM	O
,	O
SP1	O
(	O
released	O
June	O
20	O
,	O
2001	O
)	O
,	O
and	O
SP2	O
(	O
released	O
June	O
11	O
,	O
2002	O
)	O
were	O
distributed	O
in	O
parallel	O
with	O
the	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
2000	O
service	O
packs	O
,	O
and	O
could	O
also	O
be	O
downloaded	O
from	O
the	O
Microsoft	O
website	O
.	O
</s>
<s>
Beginning	O
with	O
this	O
version	O
of	O
MDAC	O
,	O
Microsoft	B-Application
Jet	I-Application
,	O
Microsoft	B-Application
Jet	I-Application
OLE	B-Language
DB	I-Language
Provider	I-Language
,	O
and	O
the	O
ODBC	B-Application
Desktop	O
Database	B-Application
Drivers	I-Application
were	O
not	O
included	O
.	O
</s>
<s>
Microsoft	O
also	O
released	O
an	O
alert	O
warning	O
that	O
MDAC	O
2.6	O
should	O
not	O
be	O
installed	O
on	O
an	O
SQL	B-Application
Server	I-Application
7.0	O
Cluster	O
,	O
because	O
"	O
if	O
you	O
install	O
MDAC	O
2.6	O
or	O
later	O
on	O
any	O
node	O
in	O
the	O
cluster	O
,	O
directly	O
or	O
through	O
the	O
installation	O
of	O
another	O
program	O
,	O
it	O
may	O
cause	O
a	O
catastrophic	O
failure	O
of	O
the	O
SQL	B-Application
Server	I-Application
Agent	O
or	O
other	O
SQL	B-Application
Server	I-Application
services.	O
"	O
</s>
<s>
This	O
issue	O
affected	O
Veritas	O
Software	O
's	O
Backup	O
Exec	O
9.0	O
for	O
Windows	B-Application
Servers	O
,	O
because	O
it	O
installs	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
2000	O
Desktop	O
Engine	O
(	O
MSDE	B-Application
2000	O
)	O
as	O
its	O
database	O
.	O
</s>
<s>
A	O
refresh	O
release	O
was	O
issued	O
in	O
April	O
2002	O
through	O
the	O
release	O
of	O
Windows	B-Application
XP	I-Application
and	O
through	O
Microsoft	O
's	O
website	O
.	O
</s>
<s>
Hebrew	O
and	O
Arabic	O
were	O
only	O
available	O
through	O
Windows	B-Application
XP	I-Application
.	O
</s>
<s>
The	O
main	O
feature	O
change	O
was	O
support	O
for	O
Microsoft	O
's	O
64-bit	B-Device
operating	O
system	O
,	O
however	O
support	O
for	O
Banyan	B-Operating_System
VINES	I-Operating_System
was	O
also	O
dropped	O
from	O
this	O
version	O
of	O
MDAC	O
.	O
</s>
<s>
There	O
were	O
several	O
known	O
issues	O
:	O
MDAC	O
2.7	O
continued	O
causing	O
connectivity	O
problems	O
on	O
clustered	O
servers	O
running	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
6.5	O
or	O
SQL	B-Application
Server	I-Application
7.0	O
,	O
with	O
no	O
workaround	O
provided	O
by	O
Microsoft	O
.	O
</s>
<s>
When	O
creating	O
or	O
configuring	O
ODBC	B-Application
data	B-General_Concept
source	I-General_Concept
names	I-General_Concept
(	O
DSNs	O
)	O
using	O
the	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
ODBC	B-Application
driver	B-Application
the	O
network	O
library	O
protocol	O
might	O
unexpectedly	O
switch	O
to	O
TCP/IP	B-Protocol
,	O
even	O
if	O
the	O
DSN	O
was	O
configured	O
to	O
use	O
named	B-Operating_System
pipes	I-Operating_System
.	O
</s>
<s>
This	O
issue	O
was	O
found	O
by	O
InfoWorld	O
reporter	O
Randall	O
C	B-Language
.	O
Kennedy	O
,	O
who	O
identified	O
that	O
the	O
change	O
was	O
actually	O
made	O
in	O
MDAC	O
2.6	O
but	O
was	O
never	O
documented	O
.	O
</s>
<s>
It	O
was	O
discovered	O
when	O
testing	O
client/server	O
database	O
workloads	O
on	O
a	O
Windows	B-Application
XP	I-Application
computer	O
;	O
InfoWorld	O
claims	O
that	O
although	O
overall	O
server	O
CPU	O
utilization	O
rose	O
by	O
only	O
8	O
percent	O
using	O
TCP/IP	B-Protocol
,	O
context	B-Operating_System
switches	I-Operating_System
per	O
second	O
dropped	O
by	O
more	O
than	O
150	O
percent	O
(	O
which	O
is	O
of	O
course	O
impossible	O
because	O
you	O
would	O
then	O
have	O
a	O
negative	O
context	B-Operating_System
switch	I-Operating_System
rate	O
-	O
the	O
drop	O
is	O
either	O
33%	O
or	O
60%	O
depending	O
on	O
which	O
planet	O
the	O
author	O
was	O
on	O
at	O
the	O
time	O
of	O
writing	O
)	O
for	O
a	O
10-user	O
workload	O
.	O
</s>
<s>
Windows	B-Application
XP	I-Application
users	O
also	O
sometimes	O
experienced	O
problems	O
connecting	O
to	O
SQL	B-Application
Server	I-Application
because	O
SQL	B-Application
Server	I-Application
attempts	O
to	O
use	O
certificates	O
it	O
finds	O
on	O
the	O
local	O
computer	O
,	O
however	O
if	O
there	O
is	O
more	O
than	O
one	O
certificate	O
available	O
it	O
did	O
not	O
know	O
which	O
one	O
to	O
use	O
.	O
</s>
<s>
When	O
attempting	O
to	O
use	O
Microsoft	B-Application
Analysis	I-Application
Services	I-Application
2000	O
RTM	O
,	O
an	O
error	O
would	O
sometimes	O
appear	O
when	O
trying	O
to	O
browse	O
cubes	O
.	O
</s>
<s>
Microsoft	O
also	O
discovered	O
a	O
problem	O
in	O
Windows	B-Application
95	I-Application
,	O
Windows	B-Device
98	I-Device
,	O
and	O
Windows	B-Device
Me	I-Device
's	O
setup	O
program	O
which	O
prevented	O
the	O
MDAC	O
installation	O
program	O
from	O
rolling	O
back	O
when	O
it	O
encountered	O
an	O
installation	O
error	O
.	O
</s>
<s>
David	O
Litchfield	O
of	O
Next	O
Generation	O
Security	O
Software	O
Ltd	O
reported	O
a	O
security	O
vulnerability	O
that	O
results	O
because	O
one	O
of	O
the	O
ODBC	B-Application
functions	O
in	O
MDAC	O
that	O
is	O
used	O
to	O
connect	O
to	O
data	O
sources	O
contained	O
an	O
unchecked	O
buffer	O
.	O
</s>
<s>
Another	O
vulnerability	O
that	O
was	O
fixed	O
was	O
one	O
whereby	O
an	O
attacker	O
could	O
respond	O
to	O
an	O
SQL	B-Application
Server	I-Application
discovery	O
message	O
broadcast	O
by	O
clients	O
with	O
a	O
specially	O
crafted	O
packet	O
that	O
could	O
cause	O
a	O
buffer	O
overflow	O
.	O
</s>
<s>
MDAC	O
2.8	O
was	O
released	O
in	O
August	O
2003	O
and	O
distributed	O
with	O
Microsoft	B-Application
Windows	I-Application
Server	I-Application
2003	I-Application
,	O
as	O
well	O
as	O
on	O
Microsoft	O
's	O
website	O
.	O
</s>
<s>
It	O
did	O
not	O
introduce	O
any	O
new	O
features	O
to	O
the	O
product	O
but	O
fixed	O
a	O
number	O
of	O
bugs	O
and	O
security	O
issues	O
a	O
reg	B-Protocol
file	I-Protocol
(	O
automates	O
changes	O
to	O
the	O
registry	O
)	O
was	O
removed	O
that	O
made	O
the	O
server	O
run	O
in	O
an	O
"	O
unsafe	O
"	O
mode	O
whereby	O
the	O
RDS	O
could	O
be	O
exploited	O
to	O
gain	O
unauthorized	O
access	O
to	O
the	O
system	O
and	O
a	O
new	O
restriction	O
was	O
imposed	O
on	O
the	O
length	O
of	O
the	O
Shape	O
query	O
string	O
.	O
</s>
<s>
There	O
were	O
also	O
several	O
ODBC	B-Application
Administrator	O
changes	O
.	O
</s>
<s>
However	O
,	O
Microsoft	O
have	O
created	O
a	O
new	O
component	O
called	O
the	O
SQL	B-Language
Native	O
Client	O
(	O
SQLNCLI	O
)	O
,	O
which	O
is	O
a	O
stand-alone	O
data	O
access	O
API	B-Application
that	O
has	O
combined	O
the	O
OLE	B-Language
DB	I-Language
and	O
ODBC	B-Application
libraries	O
into	O
one	O
DLL	O
.	O
</s>
<s>
Windows	B-Device
7	I-Device
SP1	O
has	O
broken	O
forward	B-General_Concept
compatibility	I-General_Concept
of	O
MDAC	O
2.8	O
.	O
</s>
<s>
Software	O
compiled	O
on	O
Windows	B-Device
7	I-Device
SP1	O
that	O
relies	O
on	O
MDAC	O
ADO	B-Library
will	O
not	O
work	O
on	O
Windows	B-Application
versions	O
prior	O
to	O
Windows	B-Device
7	I-Device
SP1	O
(	O
including	O
Windows	B-Device
7	I-Device
RTM	O
,	O
Vista	B-Application
,	O
XP	B-Application
)	O
.	O
</s>
<s>
Windows	B-Application
Vista	I-Application
will	O
no	O
longer	O
use	O
MDAC	O
,	O
but	O
instead	O
use	O
Windows	B-Application
DAC	O
,	O
which	O
consists	O
of	O
updated	O
versions	O
of	O
ADO	B-Library
,	O
OLE	B-Language
DB	I-Language
,	O
and	O
ODBC	B-Application
components	O
.	O
</s>
<s>
According	O
to	O
Microsoft	O
,	O
"	O
Windows	B-Application
DAC	O
includes	O
some	O
changes	O
to	O
work	O
with	O
Windows	B-Application
Vista	I-Application
,	O
but	O
is	O
almost	O
entirely	O
functionally	O
equivalent	O
to	O
MDAC	O
2.8.	O
"	O
</s>
<s>
For	O
Windows	B-Application
2000	I-Application
,	O
Windows	B-Application
XP	I-Application
and	O
Windows	B-Application
Server	I-Application
2003	I-Application
,	O
one	O
way	O
to	O
check	O
is	O
via	O
Microsoft	O
's	O
program	O
,	O
which	O
compares	O
the	O
value	O
of	O
each	O
installed	O
MDAC	O
DLL	O
to	O
the	O
MDAC	O
file	O
manifest	O
.	O
</s>
<s>
The	O
second	O
way	O
is	O
to	O
check	O
the	O
key	O
HKEY_LOCAL_MACHINE	O
\Software\Microsoft\DataAccess\FullInstallVer	O
in	O
the	O
Windows	B-Protocol
registry	I-Protocol
.	O
</s>
<s>
OLE	B-Language
DB	I-Language
Provider	I-Language
for	O
the	O
ODBC	B-Application
driver	B-Application
for	O
:	O
</s>
<s>
Jet	B-Application
drivers	O
for	O
:	O
</s>
<s>
xBase	B-Language
2.5	O
SP1	O
July	O
31	O
,	O
2000	O
Windows	B-Application
2000	I-Application
SP1	O
2.5	O
SP2	O
April	O
2000	O
Windows	B-Application
2000	I-Application
SP2	O
2.5	O
SPS3	O
December	O
2003	O
Windows	B-Application
2000	I-Application
SP3	O
2.6	O
September	O
2000	O
SQL	B-Application
Server	I-Application
2000	O
Not	O
included	O
(	O
manually	O
installed	O
)	O
:	O
</s>
<s>
SQL	B-Application
Server	I-Application
2005	O
Beta	O
1	O
(	O
Removed	O
in	O
subsequent	O
releases	O
)	O
Chapter	O
11	O
Changes	O
,	O
supplementary	O
material	O
to	O
"	O
A	O
First	O
Look	O
at	O
SQL	B-Application
Server	I-Application
2005	O
for	O
Developers	O
"	O
by	O
Bob	O
Beauchemin	O
,	O
Niels	O
Berglund	O
,	O
and	O
Dan	O
Sullivan	O
.	O
</s>
