根据另一个表中的日期查找重复行[已关闭]

编辑: 你的问题看起来很含糊,我可能不明白。

但是无论如何,根据您的预期输出,您的第一个查询是可以的,只需更改 HAVING 从句并使其成为 WHERE 条款

select T1.dno, count(T1.dno) count
from T1
left join T2 on T1.jno = T2.jno
WHERE T2.DATE = 2017
group by T1.dno

下面的查询应该可以帮助您

select rno, count(date) cnt
from t2
where t2.rno in (select T1.rno from T1)
group by rno
having count(date) > 1 -- this will get you the duplicate records

您的预期输出可以通过以下查询获得:

SELECT t1.dno, COUNT(DISTINCT t2.date) AS count
FROM T1 t1
LEFT JOIN T2 t2
    ON t1.jno = t2.jno
GROUP BY t1.dno;

但不清楚是什么角色 T1 在这里玩耍。

你可以用这个。它会告诉你那一年以及那一年有多少记录被退回。

select t1.dno,t2.date,count(t2.date) 
from t1 inner join t2 on t2.jno = t1.jno
group by t1.dno,t2.date
having count(t2.date) >1