在 postgresql 中搜索跨字段重复项

Question

我有一张联系人表。该表包含一个 mobile_phone 列以及一个 home_phone 列。我想获取所有重复的联系人，其中重复是两个共享电话号码的联系人。如果联系人 A 的 mobile_phone 与联系人 B 的 home_phone 匹配，则这也是重复的。 这是应该匹配的三个联系人的示例。

contact_id|mobile_phone|home_phone|other columns such as email.......|...
-------------------------------------------------------------------------
111       |9748777777  |1112312312|..................................|...
112       |1112312312  |null      |..................................|...
113       |9748777777  |0001112222|..................................|...

这是一个查找重复项的查询，而不是跨字段。

select mobile_phone from contacts group by mobile_phone HAVING count(*) > 1 order by mobile_phone

Answer 1

使用窗口函数：

select c.*
from (select c.*, count(*) over (partition by mobile_phone) as cnt
      from contacts c
     ) c
where cnt > 1;

Answer 2

要查找具有（跨列）重复电话号码的所有行：

SELECT *
FROM   contacts c
WHERE  EXISTS (
   SELECT FROM contacts x
   WHERE  x.mobile_phone IN (c.mobile_phone, c.home_phone)
       OR x.home_phone   IN (c.mobile_phone, c.home_phone)
   AND x.contact_id <> c.contact_id  -- except self
   );

要在两列中查找所有重复的电话号码：

SELECT DISTINCT phone
FROM  (
   SELECT mobile_phone AS phone
   FROM   contacts c
   WHERE  EXISTS (
      SELECT FROM mobile_phone x
      WHERE  c.mobile_phone IN (x.mobile_phone, x.home_phone)
      AND    c.contact_id <> x.contact_id  -- except self
      )
   UNION ALL
   SELECT home_phone
   FROM   contacts c
   WHERE  EXISTS (
      SELECT FROM mobile_phone x
      WHERE  c.home_phone = x.home_phone   -- cross-over covered by 1s SELECT
      AND    c.contact_id <> x.contact_id  -- except self
      )
   ) sub;

在同一行的两列中重复相同的数字不符合条件。我不认为你会想要包括那些。 （仍然是可能值得用 CHECK 约束禁止的噪音。）