thanks in advance to help me out on this, I am new to SQL Server and need your expert help, I want to return all values from LEFT table even no record in right table and MAX(MOT Expiry) or MAX(Road Tax) Expiry.
I tried this query but cant get the required results
SELECT Vehicle.id,vehicle.registrationMark, vehicle.status, RoadTax.Expiry, MOT.Expiry
FROM Vehicle
LEFT JOIN RoadTax ON Vehicle.id = RoadTax.VehicleID
LEFT JOIN MOT ON Vehicle.id = MOT.VehicleID;
For making it clear look at this example. I want to return all Vehicles from Vehicle table with their max TAX and MOT Expiry. even a record for a vehicle is not available in Road Tax or MOT Table.
Vehicle Table
---------------------------------
| ID | RegistrationMark | Status |
---------------------------------
| 1 | ABC | Active |
| 2 | DEF | Active |
| 3 | GHI | Active |
---------------------------------
Road Tax Table
------------------------------
| ID | VehicleID | Expiry |
------------------------------
| 1 | 1 | 10/10/2013 |
| 2 | 1 | 10/10/2014 |
| 3 | 2 | 20/12/2014 |
------------------------------
MOT Table
-------------------------------
| ID | VehicleID | Expiry |
-------------------------------
| 1 | 2 | 25/01/2015 |
-------------------------------
Result I want
-----------------------------------------------------------
| ID | RegistrationMark | Status | TaxExpiry | MOTExpiry |
-----------------------------------------------------------
| 1 | ABC | Active | 10/10/2014 | NULL |
| 2 | DEF | Active | 20/12/2014 | 25/01/2015 |
| 3 | GHI | Active | NULL | NULL |
-----------------------------------------------------------
Thank you so much for your help.
Seems like you were on the right track with your query - you just need to add the aggregation:
SELECT Vehicle.id,vehicle.registrationMark, vehicle.status
, Max(RoadTax.Expiry) as LatestTax_Exp
, Max(MOT.Expiry) as LatestMOT_Exp
FROM Vehicle
LEFT JOIN RoadTax ON Vehicle.id = RoadTax.VehicleID
LEFT JOIN MOT ON Vehicle.id = MOT.VehicleID;
group by vehicle.ID, vehicle.Registrationmark, vehicle.status
or, if I have misunderstood what you wanted and vehicles can have more than one status or registration, try:
SELECT Vehicle.id,vehicle.registrationMark, vehicle.status
, Max(RoadTax.Expiry) over (partition by Vehicle.ID) as LatestRT_Exp
, Max(MOT.Expiry) over (partition by Vehicle.ID) as LatestMOT_Exp
FROM Vehicle
LEFT JOIN RoadTax ON Vehicle.id = RoadTax.VehicleID
LEFT JOIN MOT ON Vehicle.id = MOT.VehicleID;
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