Question

Please click here for sample tables and description.

I have two tables ‘VEHICLE’ and ‘VEHICLE_CLASS’ as per attached images.

I need a query to get the result rows with how many VEHICLES each VEHICLE_CLASS has grouped by status as shown in attached image.

The query should be generic so that it can be used in any database (MySQL/Oracle/MSSQL/DB2)

Please help.

CREATE TABLE VEHICLE 
(
    VEHICLE_ID varchar(20), 
    VEHICLE_CLASS_ID varchar(30),
    STATUS int
);

CREATE TABLE VEHICLE_CLASS
(
    VEHICLE_CLASS_ID varchar(30),
    VEHICLE_CLASS_NAME varchar(30)
);

INSERT INTO VEHICLE
   (VEHICLE_ID, VEHICLE_CLASS_ID, STATUS)
VALUES
   ('vehicle_001', 'vehicle_class_001', 0),
   ('vehicle_002', 'vehicle_class_002', 1),
   ('vehicle_003', 'vehicle_class_003', 2),
   ('vehicle_004', 'vehicle_class_001', 0),
   ('vehicle_005', 'vehicle_class_002', 2),
   ('vehicle_006', 'vehicle_class_001', 0),
   ('vehicle_007', NULL, 1);


INSERT INTO VEHICLE_CLASS
   (VEHICLE_CLASS_ID, VEHICLE_CLASS_NAME)
VALUES
   ('vehicle_class_001', 'ABC'),
   ('vehicle_class_002', 'BCD'),
   ('vehicle_class_003', 'EFG'); 

Here is the query that I tried but didn’t able to get desired result:

SELECT veh.VEHICLE_CLASS_ID, vehclass.VEHICLE_CLASS_NAME, 
    SUM( CASE WHEN veh.STATUS=2 THEN COUNT(veh.VEHICLE_ID) end) Completed,
    SUM( CASE WHEN veh.STATUS!=2 THEN COUNT(veh.VEHICLE_ID) end) not_completed
FROM VEHICLE veh LEFT JOIN VEHICLE_CLASS vehclass on veh.VEHICLE_CLASS_ID = vehclass.VEHICLE_CLASS_ID
    GROUP BY veh.VEHICLE_CLASS_ID having veh.VEHICLE_CLASS_ID is not null;

Answer 1

You where pretty close. Instead of SUM( CASE WHEN veh.STATUS=2 THEN COUNT(veh.VEHICLE_ID) its, then 1 and also you need to group by VEHICLE_CLASS_NAME (except in MySQL but you wanted it to work in the others).

SELECT veh.VEHICLE_CLASS_ID, 
       vehclass.VEHICLE_CLASS_NAME, 
       Sum(CASE 
             WHEN veh.STATUS = 2 THEN 1 
           END) Completed, 
       Sum(CASE 
             WHEN veh.STATUS <> 2 THEN 1 
           END) not_completed 
FROM   VEHICLE veh 
       LEFT JOIN VEHICLE_CLASS vehclass 
         ON veh.VEHICLE_CLASS_ID = vehclass.VEHICLE_CLASS_ID 
GROUP  BY veh.VEHICLE_CLASS_ID, 
          vehclass.VEHICLE_CLASS_NAME 
HAVING veh.VEHICLE_CLASS_ID IS NOT NULL; 

DEMO SQL Server

DEMO MySQL

DEMO Oracle

Notes

• As Lamak pointed out <> is typically used but it seems != to be well supported but you’ll need to test
• I didn’t add Else 0 Because the image included a blank space in the SUM_not_completed. You may choose to do this or add a COALACE if you do want zeros
• If you know you’re in MySQL you can remove the CASE and do Sum(veh.STATUS = 2) Completed