27,581
社区成员




--try
select T1.*, N=coalesce(ta.N, tb.N, tc.N)
from T1 left join T2 ta on T1.A=ta.M
left join T2 tb on T1.A=tb.M
left join T2 tc on T1.A=tc.M
where coalesce(ta.N, tb.N, tc.N) is not null
--try
select T1.*, N=coalesce(ta.N, tb.N, tc.N)
from T1 left join T2 ta on T1.A=ta.M
left join T2 tb on T1.A=tb.M
left join T2 tc on T1.A=tc.M
select distinct t1.* , t2.* from t1 , t2 where t1.a = t2.m or t1.b = t2.m or t1.c = t2.m
select t1.* from t1 , t2 where t1.a = t2.m or t1.b = t2.m or t1.c = t2.m