<s>
A	O
WHERE	O
clause	O
in	O
SQL	B-Language
specifies	O
that	O
a	O
SQL	B-Language
Data	B-Language
Manipulation	I-Language
Language	I-Language
(	O
DML	O
)	O
statement	O
should	O
only	O
affect	O
rows	B-Application
that	O
meet	O
specified	O
criteria	O
.	O
</s>
<s>
WHERE	O
clauses	O
are	O
not	O
mandatory	O
clauses	O
of	O
SQL	B-Language
DML	O
statements	O
,	O
but	O
can	O
be	O
used	O
to	O
limit	O
the	O
number	O
of	O
rows	B-Application
affected	O
by	O
a	O
SQL	B-Language
DML	O
statement	O
or	O
returned	O
by	O
a	O
query	O
.	O
</s>
<s>
In	O
brief	O
SQL	B-Language
WHERE	I-Language
clause	O
is	O
used	O
to	O
extract	O
only	O
those	O
results	O
from	O
a	O
SQL	B-Language
statement	O
,	O
such	O
as	O
:	O
SELECT	O
,	O
INSERT	O
,	O
UPDATE	O
,	O
or	O
DELETE	B-Language
statement	O
.	O
</s>
<s>
WHERE	O
is	O
an	O
SQL	B-Language
reserved	O
word	O
.	O
</s>
<s>
The	O
WHERE	O
clause	O
is	O
used	O
in	O
conjunction	O
with	O
SQL	B-Language
DML	O
statements	O
,	O
and	O
takes	O
the	O
following	O
general	O
form	O
:	O
</s>
<s>
all	O
rows	B-Application
for	O
which	O
the	O
predicate	O
in	O
the	O
WHERE	O
clause	O
is	O
True	O
are	O
affected	O
(	O
or	O
returned	O
)	O
by	O
the	O
SQL	B-Language
DML	O
statement	O
or	O
query	O
.	O
</s>
<s>
Rows	B-Application
for	O
which	O
the	O
predicate	O
evaluates	O
to	O
False	O
or	O
Unknown	O
(	O
NULL	B-Language
)	O
are	O
unaffected	O
by	O
the	O
DML	O
statement	O
or	O
query	O
.	O
</s>
<s>
The	O
following	O
query	O
returns	O
only	O
those	O
rows	B-Application
from	O
table	O
mytable	O
where	O
the	O
value	O
in	O
column	B-Application
mycol	O
is	O
greater	O
than	O
100	O
.	O
</s>
<s>
The	O
following	O
DELETE	B-Language
statement	O
removes	O
only	O
those	O
rows	B-Application
from	O
table	O
mytable	O
where	O
the	O
column	B-Application
mycol	O
is	O
either	O
NULL	B-Language
or	O
has	O
a	O
value	O
that	O
is	O
equal	O
to	O
100	O
.	O
</s>
<s>
Simple	O
predicates	O
use	O
one	O
of	O
the	O
operators	O
=	O
,	O
<>, >, >	O
=	O
,	O
<	O
,	O
<=	O
,	O
IN	O
,	O
BETWEEN	O
,	O
LIKE	O
,	O
IS	O
NULL	B-Language
or	O
IS	O
NOT	O
NULL	B-Language
.	O
</s>
<s>
The	O
following	O
example	O
deletes	B-Language
rows	B-Application
from	O
mytable	O
where	O
the	O
value	O
of	O
mycol	O
is	O
greater	O
than	O
100	O
,	O
and	O
the	O
value	O
of	O
item	O
is	O
equal	O
to	O
the	O
string	B-Language
literal	I-Language
'	O
Hammer	O
 '	O
:	O
</s>
<s>
All	O
rows	B-Application
match	O
the	O
predicate	O
if	O
their	O
value	O
is	O
one	O
of	O
the	O
candidate	O
set	O
of	O
values	O
.	O
</s>
<s>
All	O
rows	B-Application
match	O
the	O
predicate	O
if	O
their	O
value	O
is	O
between	O
'	O
value1	O
 '	O
and	O
'	O
value2	O
 '	O
,	O
inclusive	O
.	O
</s>
