para SQL Server 2005 e acima, tente:
;WITH SalesScore AS (
SELECT
s.PK_ID as S_PK
,c.PK_ID AS c_PK
,CASE
WHEN c.PK_ID IS NULL THEN 0
ELSE CASE WHEN s.ServiceId=c.ServiceId THEN 1 ELSE 0 END
+CASE WHEN (s.Address=c.Address AND s.Zip=c.Zip) THEN 1 ELSE 0 END
+CASE WHEN s.EmailAddress=c.EmailAddress THEN 1 ELSE 0 END
+CASE WHEN s.HomePhone=c.HomePhone THEN 1 ELSE 0 END
END AS Score
FROM Sales s
LEFT OUTER JOIN Customers c ON s.ServiceId=c.ServiceId
OR (s.Address=c.Address AND s.Zip=c.Zip)
OR s.EmailAddress=c.EmailAddress
OR s.HomePhone=c.HomePhone
)
SELECT
s.*,c.*
FROM (SELECT
S_PK,MAX(Score) AS Score
FROM SalesScore
GROUP BY S_PK
) dt
INNER JOIN Sales s ON dt.s_PK=s.PK_ID
INNER JOIN SalesScore ss ON dt.s_PK=s.PK_ID AND dt.Score=ss.Score
LEFT OUTER JOIN Customers c ON ss.c_PK=c.PK_ID
EDITAR Eu odeio escrever tanto código real quando não havia shema dado, porque eu não posso realmente executar isso e ter certeza de que funciona. No entanto, para responder à questão de como lidar com empates usando a data da última transação, aqui está uma versão mais recente do código acima:
;WITH SalesScore AS (
SELECT
s.PK_ID as S_PK
,c.PK_ID AS c_PK
,CASE
WHEN c.PK_ID IS NULL THEN 0
ELSE CASE WHEN s.ServiceId=c.ServiceId THEN 1 ELSE 0 END
+CASE WHEN (s.Address=c.Address AND s.Zip=c.Zip) THEN 1 ELSE 0 END
+CASE WHEN s.EmailAddress=c.EmailAddress THEN 1 ELSE 0 END
+CASE WHEN s.HomePhone=c.HomePhone THEN 1 ELSE 0 END
END AS Score
FROM Sales s
LEFT OUTER JOIN Customers c ON s.ServiceId=c.ServiceId
OR (s.Address=c.Address AND s.Zip=c.Zip)
OR s.EmailAddress=c.EmailAddress
OR s.HomePhone=c.HomePhone
)
SELECT
*
FROM (SELECT
s.*,c.*,row_number() over(partition by s.PK_ID order by s.PK_ID ASC,c.LastTransaction DESC) AS RankValue
FROM (SELECT
S_PK,MAX(Score) AS Score
FROM SalesScore
GROUP BY S_PK
) dt
INNER JOIN Sales s ON dt.s_PK=s.PK_ID
INNER JOIN SalesScore ss ON dt.s_PK=s.PK_ID AND dt.Score=ss.Score
LEFT OUTER JOIN Customers c ON ss.c_PK=c.PK_ID
) dt2
WHERE dt2.RankValue=1
