<s>
The	O
SQL	B-Language
From	O
clause	O
is	O
the	O
source	O
of	O
a	O
rowset	O
to	O
be	O
operated	O
upon	O
in	O
a	O
Data	B-Language
Manipulation	I-Language
Language	I-Language
(	O
DML	O
)	O
statement	O
.	O
</s>
<s>
From	O
clauses	O
are	O
very	O
common	O
,	O
and	O
will	O
provide	O
the	O
rowset	O
to	O
be	O
exposed	O
through	O
a	O
Select	B-Language
statement	O
,	O
the	O
source	O
of	O
values	O
in	O
an	O
Update	B-Language
statement	O
,	O
and	O
the	O
target	O
rows	O
to	O
be	O
deleted	O
in	O
a	O
Delete	B-Language
statement	O
.	O
</s>
<s>
FROM	O
is	O
an	O
SQL	B-Language
reserved	O
word	O
in	O
the	O
SQL	B-Language
standard	O
.	O
</s>
<s>
The	O
FROM	O
clause	O
is	O
used	O
in	O
conjunction	O
with	O
SQL	B-Language
statements	O
,	O
and	O
takes	O
the	O
following	O
general	O
form	O
:	O
</s>
<s>
The	O
From	O
clause	O
is	O
technically	O
required	O
in	O
relational	B-Algorithm
algebra	I-Algorithm
and	O
in	O
most	O
scenarios	O
to	O
be	O
useful	O
.	O
</s>
<s>
However	O
many	O
relational	O
DBMS	O
implementations	O
may	O
not	O
require	O
it	O
for	O
selecting	O
a	O
single	O
value	O
,	O
or	O
single	O
row	O
-	O
known	O
as	O
DUAL	B-Application
table	I-Application
in	O
Oracle	B-General_Concept
database	I-General_Concept
.	O
</s>
<s>
Other	O
systems	O
will	O
require	O
a	O
From	O
statement	O
with	O
a	O
keyword	O
,	O
even	O
to	O
select	B-Language
system	O
data	O
.	O
</s>
