select a.station,a.rq,a.bz,b.pynd,c.fynd
from a,b,c
where a.station=b.station(+)
and a.station=c.station(+)
and a.rq=c.rq(+)
and a.rq=c.rq(+)
from a,b,c
where a.station=b.station(+)
and a.station=c.station(+)
and a.rq=c.rq(+)
and a.rq=c.rq(+)
a.rq=b.rq(+) and a.station=c.station(+) and a.rq=c.rq(+);
我想问一下,+是什么意思,是连接吗?100分你得定了