sql - SQL for set of all in group by

Question

假设我有表 foo

美国广播公司
===============
1 1 1
1 2 3
1 2 4
1 3 6
2 2 6     

我想要所有 C 的集合，其中我有一个重复的 AB。就像是：

select all(C) from foo group by a, b having count(b) > 1

我希望结果是

全部(C)
===
 3
 4

在 Oracle SQL 中是否有一种简单的方法可以做到这一点？

Answer 1

SELECT t1.c
  FROM foo t1
       JOIN foo t2 ON (t1.a = t2.a AND 
                       t1.b = t2.b AND 
                       t1.rowid != t2.rowid)

应该给你你所追求的。更有效的可能是使用分析函数

SELECT c
  FROM (SELECT f.*,
               count(*) over (partition by a, b) cnt
          FROM foo f)
 WHERE cnt > 1

Answer 2

尝试这个：

SELECT C
FROM
(select C, COUNT(*) OVER(PARTITION BY A, B) AS DUPLICATES
from MY_TABLE) AS RESULTS
WHERE DUPLICATES > 1

Answer 3

我想到了。我用了

select f.c from foo f
join (select a, b from foo group by a, b having count(c) > 1) dupes
on dupes.a = f.a and dupes.b = f.b;