Select subset of duplicate records in SQL Server

Question

I need to select a subset of duplicate records in SQL Server 2016. Below is the data set and the code used. I need to select only duplicates highlighted in red. Basically I need only those duplicate records that have matching LName, FName, dateOfBirth, StreetAddress values and in the Source the nave NUll. At the same time, I need only those records that also match in the abovementioned fields and have Source value of "Company XYZ"

IF OBJECT_ID('tempdb..#Dataset') IS NOT NULL DROP TABLE #Dataset
GO

create table #Dataset 
(
    ID int not null,
    LName varchar(50) null,
    Fname varchar(50) null,
    DateOfBirth varchar(50) null,
    StreetAddress varchar(50) null,
    Source varchar(50) null,
)

insert into #Dataset (ID, LName, Fname, DateOfBirth, StreetAddress, Source)
values
('1', 'John', 'Ganske', '37171', '  1223 Sunrise St', 'Company XYZ'),
('2', 'John', 'Ganske', '37171', '  1233 Sunrise St', 'Company XYZ'),
('4', 'Brent', 'Paine', '20723', '  5443 Fox Dr', Null),
('3', 'Brent', 'Paine', '20723', '  5443 Fox Dr', 'Company XYZ'),
('5', 'Adam', 'Smith', '22805', '  1254 Lake Ridge Ct', Null),
('6', 'Adam', 'Smith', '22805', '  1254 Lake Ridge Ct', Null),
('7', 'Adam', 'Smith', '22805', '  1254 Lake Ridge Ct', 'Company XYZ'),
('8', 'Timothy', 'Johnson', '36165', '  1278 Lee H-W', Null),
('9', 'Timothy', 'Johnson', '36165', '  1278 Lee H-W', Null),
('10', 'Judy', 'Wilson', '32579', '  5678 Dotties Dr', 'Company XYZ'),
('12', 'Peter', 'Pan', '37507', NULL, Null),
('11', 'Peter', 'Pan', '37507', NULL, 'Company XYZ');

--select * from #Dataset

select d.ID, d.LName, d.Fname, d.DateOfBirth, d.StreetAddress, d.Source 
from  #Dataset d
inner join (select 
                LName, Fname, DateOfBirth, StreetAddress 
            from #Dataset
            --where Source is not null
            group by 
                LName, Fname, DateOfBirth, StreetAddress 
            having count(*) > 1 ) b 
            on  d.LName = b.LName 
                and 
                d.Fname = b.Fname 
                and 
                d.DateOfBirth = b.DateOfBirth
                and
                d.StreetAddress = b.StreetAddress   

left outer join (select min(ID) as ID from #Dataset
            group by  LName, Fname, DateOfBirth, StreetAddress 
            having count(*) > 1 ) c 
            on d.ID = c.ID

My output looks like this one below:

Answer 1

You could use ROW_NUMBER:

WITH cte AS (
 SELECT *,ROW_NUMBER() OVER(PARTITION BY LName,Fname,DateOfBirth,StreetAddress 
                            ORDER BY ID DESC) rn
 FROM #Dataset
)
SELECT *
FROM cte 
WHERE rn > 1
ORDER BY ID;

db<>fiddle demo

EDIT:

WITH cte AS (
SELECT *, 
  ROW_NUMBER() OVER(PARTITION BY LName, Fname, DateOfBirth, StreetAddress 
                    ORDER BY ID DESC) rn,
  SUM(CASE WHEN Source = 'Company XYZ' THEN 1 ELSE 0 END) 
               OVER(PARTITION BY LName, Fname, DateOfBirth, StreetAddress) AS cnt
FROM #Dataset
)
SELECT *
FROM cte 
WHERE rn > 1
  AND cnt > 0
  AND [Source] IS NULL
ORDER BY ID;

db<>fiddle demo2

EDIT 2:

WITH cte AS (
SELECT *, 
  SUM(CASE WHEN Source IS NULL THEN 1 ELSE 0 END) OVER(PARTITION BY LName, Fname, DateOfBirth, StreetAddress) c1,
  SUM(CASE WHEN Source = 'Company XYZ' THEN 1 ELSE 0 END) OVER(PARTITION BY LName, Fname, DateOfBirth, StreetAddress) AS c2,
  COUNT(*) OVER(PARTITION BY LName, Fname, DateOfBirth, StreetAddress) c3
FROM #Dataset
)
SELECT *
FROM cte 
WHERE c1 > 0
  AND c2 > 0
  AND c3 > 1
  AND Source IS NULL
ORDER BY ID;

db<>fiddle demo3