q*j
发帖数: 156 | 1 select a.f1, a.f2
from a
except
select a.f1, a.f2
from a, b
where a.f1=b.f1
and a.f2=b.f2 | a*****a
发帖数: 438 | 2 thanks qqj yet this doesnt work either:(
the one access offers is:
select a.f1, a.f2
from a LEFT JOIN b on a.f1 = b.f1
where (((a.f1) IS NULL));
who can explain LEFT JOIN for me?
tia.
【在 q*j 的大作中提到】
: select a.f1, a.f2
: from a
: except
: select a.f1, a.f2
: from a, b
: where a.f1=b.f1
: and a.f2=b.f2
| q*j
发帖数: 156 | 3 i think left join here means outer join.
try this:
select a.f1, a.f2
from a
where a.f1 not in
(select a.f1 from a, b where a.f1=b.f1)
and a.f2 not in
(select a.f2 from a, b where a.f2=b.f2)
【在 a*****a 的大作中提到】
: thanks qqj yet this doesnt work either:(
: the one access offers is:
: select a.f1, a.f2
: from a LEFT JOIN b on a.f1 = b.f1
: where (((a.f1) IS NULL));
: who can explain LEFT JOIN for me?
: tia.
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