SELECT p.OwnerName, SUM(ru.MonthlyRent) AS PotentialRent, SUM(cnt) AS ExpectedRent
FROM tblRentalUnit ru
LEFT JOIN
tblProperty p
ON p.ID = ru.PropertyID
OUTER APPLY
(
SELECT COUNT(t.id) * ru.MonthlyRent AS cnt
FROM tblTenant t
WHERE t.UnitID = ru.ID
) td
GROUP BY p.OwnerName
Вот тестовый скрипт для проверки:
WITH tblRentalUnit AS
(
SELECT 1 AS id, 100 AS MonthlyRent, 1 AS PropertyID
UNION ALL
SELECT 2 AS id, 300 AS MonthlyRent, 2 AS PropertyID
),
tblProperty AS
(
SELECT 1 AS id, 'Owner 1' AS OwnerName
UNION ALL
SELECT 2 AS id, 'Owner 2' AS OwnerName
),
tblTenant AS
(
SELECT 1 AS id, 1 AS UnitID
UNION ALL
SELECT 2 AS id, 1 AS UnitID
)
SELECT p.OwnerName, SUM(ru.MonthlyRent) AS PotentialRent, SUM(cnt) AS ExpectedRent
FROM tblRentalUnit ru
LEFT JOIN
tblProperty p
ON p.ID = ru.PropertyID
OUTER APPLY
(
SELECT COUNT(t.id) * ru.MonthlyRent AS cnt
FROM tblTenant t
WHERE t.UnitID = ru.ID
) td
GROUP BY p.OwnerName