<s>
A	O
savepoint	B-General_Concept
is	O
a	O
way	O
of	O
implementing	O
subtransactions	O
(	O
also	O
known	O
as	O
nested	O
transactions	O
)	O
within	O
a	O
relational	B-Application
database	I-Application
management	I-Application
system	I-Application
by	O
indicating	O
a	O
point	O
within	O
a	O
transaction	B-General_Concept
that	O
can	O
be	O
"	O
rolled	B-Application
back	I-Application
to	I-Application
"	O
without	O
affecting	O
any	O
work	O
done	O
in	O
the	O
transaction	B-General_Concept
before	O
the	O
savepoint	B-General_Concept
was	O
created	O
.	O
</s>
<s>
Multiple	O
savepoints	B-General_Concept
can	O
exist	O
within	O
a	O
single	O
transaction	B-General_Concept
.	O
</s>
<s>
Savepoints	B-General_Concept
are	O
useful	O
for	O
implementing	O
complex	O
error	O
recovery	O
in	O
database	O
applications	O
.	O
</s>
<s>
If	O
an	O
error	O
occurs	O
in	O
the	O
midst	O
of	O
a	O
multiple-statement	O
transaction	B-General_Concept
,	O
the	O
application	O
may	O
be	O
able	O
to	O
recover	O
from	O
the	O
error	O
(	O
by	O
rolling	O
back	O
to	O
a	O
savepoint	B-General_Concept
)	O
without	O
needing	O
to	O
abort	O
the	O
entire	O
transaction	B-General_Concept
.	O
</s>
<s>
A	O
savepoint	B-General_Concept
can	O
be	O
declared	O
by	O
issuing	O
a	O
SAVEPOINT	B-General_Concept
name	O
statement	O
.	O
</s>
<s>
All	O
changes	O
made	O
after	O
a	O
savepoint	B-General_Concept
has	O
been	O
declared	O
can	O
be	O
undone	O
by	O
issuing	O
a	O
ROLLBACK	B-Application
TO	O
SAVEPOINT	B-General_Concept
name	O
command	O
.	O
</s>
<s>
Issuing	O
RELEASE	O
SAVEPOINT	B-General_Concept
name	O
will	O
cause	O
the	O
named	O
savepoint	B-General_Concept
to	O
be	O
discarded	O
,	O
but	O
will	O
not	O
otherwise	O
affect	O
anything	O
.	O
</s>
<s>
Issuing	O
the	O
commands	O
ROLLBACK	B-Application
or	O
COMMIT	O
will	O
also	O
discard	O
any	O
savepoints	B-General_Concept
created	O
since	O
the	O
start	O
of	O
the	O
main	O
transaction	B-General_Concept
.	O
</s>
<s>
Savepoints	B-General_Concept
are	O
defined	O
in	O
the	O
SQL	O
standard	O
and	O
are	O
supported	O
by	O
all	O
established	O
SQL	O
relational	O
databases	O
,	O
including	O
PostgreSQL	B-Application
,	O
Oracle	B-General_Concept
Database	I-General_Concept
,	O
Microsoft	B-Application
SQL	I-Application
Server	I-Application
,	O
MySQL	B-Application
,	O
IBM	B-Application
Db2	I-Application
,	O
SQLite	B-Language
(	O
since	O
3.6.8	O
)	O
,	O
Firebird	B-Application
,	O
H2	O
Database	O
Engine	O
,	O
and	O
Informix	B-Application
(	O
since	O
version	O
11.50xC3	O
)	O
.	O
</s>
