SQL Server 2019

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select @@version;


(No column name)


Microsoft SQL Server 2019 (RTM-CU6) (KB4563110) - 15.0.4053.23 (X64) 
 Jul 25 2020 11:26:55 
 Copyright (C) 2019 Microsoft Corporation
 Express Edition (64-bit) on Windows Server 2019 Standard 10.0 <X64> (Build 17763: ) (Hypervisor)



CREATE TABLE table1 (
   ID integer,
   site INTEGER NULL
)
INSERT INTO table1 VALUES
(    2   ,NULL),
(    2   ,32),
(    3   ,6),
(    4   ,7),
(    8   ,12),
(    8   ,13),
(    9   ,14),
(    9   ,14);
8 rows affected

SELECT
   ID,
   site
FROM table1
WHERE ID IN (
   SELECT ID
   FROM (
      SELECT ID ,site
      FROM table1 
      GROUP BY ID ,site
   ) x
   GROUP BY ID
   HAVING count(*)>1
   )


ID
site


2
null

2
32

8
12

8
13


SELECT ID
FROM (
   SELECT ID ,site
   FROM table1 
   GROUP BY ID ,site
) x
GROUP BY ID
HAVING count(*)>1


ID


2

8

ID	site
2	null
2	32
8	12
8	13