<s>
In	O
computer	B-General_Concept
programming	I-General_Concept
,	O
create	B-General_Concept
,	I-General_Concept
read	I-General_Concept
,	I-General_Concept
update	I-General_Concept
,	I-General_Concept
and	I-General_Concept
delete	I-General_Concept
(	O
often	O
referred	O
to	O
via	O
the	O
acronym	O
CRUD	B-General_Concept
)	O
are	O
the	O
four	O
basic	O
operations	O
of	O
persistent	B-Application
storage	I-Application
.	O
</s>
<s>
CRUD	B-General_Concept
is	O
also	O
sometimes	O
used	O
to	O
describe	O
user	B-Application
interface	I-Application
conventions	O
that	O
facilitate	O
viewing	O
,	O
searching	O
,	O
and	O
changing	O
information	O
using	O
computer-based	O
forms	O
and	O
reports	O
.	O
</s>
<s>
Together	O
these	O
four	O
operations	O
make	O
up	O
the	O
basic	O
operations	O
of	O
storage	O
management	O
known	O
as	O
CRUD	B-General_Concept
:	O
Create	B-General_Concept
,	I-General_Concept
Read	I-General_Concept
,	I-General_Concept
Update	I-General_Concept
and	I-General_Concept
Delete	I-General_Concept
.	O
</s>
<s>
The	O
acronym	O
CRUD	B-General_Concept
refers	O
to	O
the	O
major	O
operations	O
which	O
are	O
implemented	O
by	O
databases	O
.	O
</s>
<s>
Each	O
letter	O
in	O
the	O
acronym	O
can	O
be	O
mapped	O
to	O
a	O
standard	O
Structured	B-Language
Query	I-Language
Language	I-Language
(	O
SQL	B-Language
)	O
statement	O
.	O
</s>
<s>
Although	O
relational	B-Application
databases	I-Application
are	O
a	O
common	O
persistence	B-Application
layer	O
in	O
software	O
applications	O
,	O
numerous	O
other	O
persistence	B-Application
layers	O
exist	O
.	O
</s>
<s>
CRUD	B-General_Concept
functionality	O
can	O
for	O
example	O
be	O
implemented	O
with	O
document	B-General_Concept
databases	I-General_Concept
,	O
object	B-Application
databases	I-Application
,	O
XML	B-Application
databases	I-Application
,	O
text	O
files	O
,	O
or	O
binary	O
files	O
.	O
</s>
<s>
Some	O
big	B-Application
data	I-Application
systems	O
do	O
not	O
implement	O
UPDATE	B-Language
,	O
but	O
have	O
only	O
a	O
timestamped	O
INSERT	B-Language
(	O
journaling	O
)	O
,	O
storing	O
a	O
completely	O
new	O
version	O
of	O
the	O
object	O
each	O
time	O
.	O
</s>
<s>
The	O
acronym	O
CRUD	B-General_Concept
also	O
appears	O
in	O
the	O
discussion	O
of	O
RESTful	B-Protocol
APIs	I-Protocol
.	O
</s>
<s>
CRUD	B-General_Concept
HTTP	O
Create	O
POST	O
,	O
PUT	O
if	O
we	O
have	O
`id`	O
or	O
`uuid`POST	O
is	O
a	O
CRUD	B-General_Concept
operation	O
in	O
the	O
same	O
way	O
as	O
SQL	B-Language
INSERT	I-Language
.	O
</s>
<s>
If	O
the	O
key	O
is	O
specified	O
in	O
INSERT	B-Language
,	O
then	O
the	O
equivalent	O
REST	O
is	O
indeed	O
PUT	O
.	O
</s>
<s>
On	O
the	O
other	O
hand	O
,	O
if	O
a	O
table	O
autogenerates	O
the	O
key	O
and	O
the	O
INSERT	B-Language
does	O
n't	O
have	O
the	O
key	O
,	O
then	O
the	O
equivalent	O
REST	O
is	O
POST	O
.	O
</s>
<s>
The	O
user	B-Protocol
agent	I-Protocol
does	O
n't	O
always	O
have	O
the	O
onus	O
of	O
knowing	O
the	O
key/id	O
when	O
creating	O
in	O
web	O
or	O
relational	B-Application
databases	I-Application
.	O
</s>
<s>
Knowing	O
the	O
key	O
when	O
creating	O
is	O
NOT	O
a	O
requirement	O
of	O
CRUD	B-General_Concept
,	O
SQL	B-Language
,	O
or	O
REST	O
.	O
</s>
<s>
In	O
HTTP	O
,	O
the	O
GET	O
(	O
read	O
)	O
,	O
PUT	O
(	O
create	O
and	O
update	B-Language
)	O
,	O
POST	O
(	O
create	O
-	O
if	O
we	O
do	O
n't	O
have	O
`id`	O
or	O
`uuid`	O
)	O
,	O
and	O
DELETE	B-Language
(	O
delete	B-Language
)	O
methods	O
are	O
CRUD	B-General_Concept
operations	O
as	O
they	O
have	O
storage	O
management	O
semantics	O
,	O
meaning	O
that	O
they	O
let	O
user	B-Protocol
agents	I-Protocol
directly	O
manipulate	O
the	O
states	O
of	O
target	O
resources	O
.	O
</s>
<s>
The	O
POST	O
method	O
,	O
on	O
the	O
other	O
hand	O
,	O
is	O
a	O
process	O
operation	O
that	O
has	O
target-resource-specific	O
semantics	O
which	O
typically	O
exceed	O
the	O
scope	O
of	O
CRUD	B-General_Concept
operations	O
.	O
</s>
<s>
CRUD	B-General_Concept
is	O
also	O
relevant	O
at	O
the	O
user	B-Application
interface	I-Application
level	O
of	O
most	O
applications	O
.	O
</s>
<s>
Other	O
variations	O
of	O
CRUD	B-General_Concept
include	O
:	O
</s>
