如何从COALESCE进行分组？ SQL

Question

SELECT 
    VehicleOwner, 
    COALESCE(CarMileage, MotorcycleMileage, BicycleMileage, 0) AS Mileage, 
    Count(*) 
FROM 
    VehicleMileage 
Group by VehicleOwner 
Having Count(*)>1 

Answer 1

我想通了什么......

SELECT b.VehicleOwner, City 
FROM (SELECT a.VehicleOwner, 
     COALESCE(a.City, (Select b.City from a INNER Place b), 
       (Select b.City from a INNER Place b)) AS City 
     FROM VehicleMileage a) AS b 
WHERE b.VehicleOwner IN (SELECT VehicleOwner 
        FROM VehicleMileage 
        GROUP BY VehicleOwner 
        HAVING COUNT(*)>1); 

Answer 2

这有效。

SELECT 
    VehicleOwner, 
    COALESCE(CarMileage, MotorcycleMileage, BicycleMileage, 0) AS Mileage, 
    Count(*) 
FROM 
    VehicleMileage 
Group by VehicleOwner, COALESCE(CarMileage, MotorcycleMileage, BicycleMileage, 0) 
Having Count(*)>1 

您还可以将COALESCE中的每列放在GROUP BY部分中。取决于你想要达到

Answer 3

SELECT 
    VehicleOwner, 
    SUM(COALESCE(CarMileage, 0)+COALESCE(MotorcycleMileage, 0)+COALESCE(BicicleMileage, 0)) AS Mileage, 
    COUNT(*) cnt 
FROM VehicleMileage 
GROUP BY VehicleOwner 
HAVING cnt > 1