这不是很简单吗,关联你没有学过吗?
select T1.T1date,t1.t2id,t2.t2name,t1.t3no,t1.memo
from t1,t2,t3
where t1.t2id = t2.t2id and t1.t3No = t3.t3no
select T1.T1date,t1.t2id,t2.t2name,t1.t3no,t1.memo
from t1,t2,t3
where t1.t2id = t2.t2id and t1.t3No = t3.t3no
------現在從表T1、T2、T3中得到的查詢中包括T1date、T2ID、T2name、T3NO、T3name、Memo這些字段
你的语句没有完全显示这些字段
from T1,T2,T3
where T1.T2ID = T2.T2ID AND T1.T3NO = T3.T3NO
from t1
left join t2 on t1.t2id=t2.t2id
left join t3 on t1.t3no=t3.t3no
select t1.T1date,t1.T2ID,t2.T2name,t1.T3NO,t3.T3name,t1.Memo
from t1
right join t2 on t1.t2id=t2.t2id
right join t3 on t1.t3no=t3.t3no
select t1.T1date,t1.T2ID,t2.T2name,t1.T3NO,t3.T3name,t1.Memo
from t1
inner join t2 on t1.t2id=t2.t2id
inner join t3 on t1.t3no=t3.t3no