SQL Server join query not retrieving proper result - sql-server

Question

Select the list of all dealers whose vehicles are never assigned to any customer i.e that vehicle is not present in PS3_VehicleBooking, and committed date is greater than today's date.
3 tables to be used are-
CREATE TABLE PS3_Dealer(
ID int IDENTITY(1,1) NOT NULL Primary KEY,
DealerID varchar(255) NULL,
DealerName varchar(255) NOT NULL,
ContactNo varchar(255) NOT NULL,
NoOfVehicles bigint NOT NULL,
CommittedDate date NOT NULL
);
create table PS3_Vehicle
(
ID int IDENTITY(1,1) NOT NULL Primary Key,
DealerID varchar(255) NOT NULL,
VehicleID varchar(255) UNIQUE NOT NULL,
VehicleName varchar(255) NOT NULL,
Capacity BIGINT NOT NULL
);
create table PS3_VehicleBooking
(
ID int IDENTITY(1,1) NOT NULL Primary Key,
BookingID varchar(255) NOT NULL UNIQUE,
VehicleID varchar(255) NOT NULL,
StartDate date NOT NULL,
EndDate date NOT NULL
);
PS3_Dealer values-
DealerID DealerName ContactNo NoOfVehicles CommittedDate
1 ng 9 5 2013-12-12
2 nikki 5 7 2013-12-25
3 nik 4 6 2013-10-11
4 hj 2 2 2014-11-10
5 pk 67 8 2013-10-10
PS3_Vehicle
DealerID VehicleID VehicleName Capacity
1 V1 ind 4
2 V2 innova 5
3 V3 innova 6
1 V4 ula 8
4 V5 hkk 2
5 V6 ghi 9
2 V7 bjhgi 4
PS3_VehicleBooking-
BookingID VehicleID StartDate EndDate
1 V1 2013-12-13 2013-12-17
2 V2 2013-10-11 2013-10-13
3 V3 2014-12-10 2014-12-13
4 V4 2012-10-10 2012-10-13
5 V2 2013-12-14 2013-12-18
expected outcome-
DealerID DealerName ContactNo NoOfVehicles CommittedDate
4 hj 2 2 2014-11-10
but i am getting-
DealerID DealerName ContactNo NoOfVehicles CommittedDate
4 hj 2 2 2014-11-10
2 Nikki 5 7 2013-12-25
i dont want dealer id 2 in result because V2 provided by dealer id 2 is present in PS3_Booking.
My query is-
SELECT h.DealerID,
h.DealerName,
h.ContactNo,
h.NoOfVehicles,
h.CommittedDate
FROM PS3_Dealer h
INNER JOIN(SELECT DealerID,
PS3_VehicleBooking.VehicleID
FROM PS3_Vehicle
LEFT JOIN PS3_VehicleBooking
ON PS3_Vehicle.VehicleID = PS3_VehicleBooking.VehicleID) w
ON h.DealerID = w.DealerID
WHERE w.VehicleID IS NULL
AND h.CommittedDate > GETDATE()
please correct where i am wrong?

Answer 1

The problem is that DealerID 2 has 2 Vehicles. One that has booking, and the other does not. When you run
SELECT DealerID,
PS3_VehicleBooking.VehicleID
FROM PS3_Vehicle
LEFT JOIN PS3_VehicleBooking
ON PS3_Vehicle.VehicleID = PS3_VehicleBooking.VehicleID
You will get one record that has DealerID 2 with NULL VehicleID and the other none NULL Vehicle ID.
You can try to the run the statement below to get the desired results (may not be the most optimal, but it is a fix to your statement):
SELECT h.DealerID,
h.DealerName,
h.ContactNo,
h.NoOfVehicles,
h.CommittedDate
FROM PS3_Dealer h
INNER JOIN(SELECT DealerID,
MAX(PS3_VehicleBooking.VehicleID) as VehicleID
FROM PS3_Vehicle
LEFT JOIN PS3_VehicleBooking
ON PS3_Vehicle.VehicleID = PS3_VehicleBooking.VehicleID
GROUP BY DealerID
) w
ON h.DealerID = w.DealerID
WHERE w.VehicleID IS NULL
AND h.CommittedDate > GETDATE()

Answer 2

Edited to actually answer the question
You were getting Nikki because there does exist a car for her (V7) that is not in the booking table.
This should exclude Nikki.
SELECT h.DealerID,
h.DealerName,
h.ContactNo,
h.NoOfVehicles,
h.CommittedDate
FROM PS3_Dealer d
WHERE NOT EXISTS
(SELECT *
FROM PS3_VehicleBookingb
JOIN PS3_Vehiclev ON b.vehicleID = v.VehicleID
JOIN PS3_Dealerd2 ON d2.dealerID = v.dealerID
WHERE d2.dealerID = d.dealerID)
AND CommittedDate > Current_date()
http://sqlfiddle.com/#!2/fb365/19