Question

Here is the MySQL query for my tables here:

SELECT vc.vehicle_class_name
, GROUP_CONCAT(CASE WHEN v.status = 2 THEN v.vehicle_id END) completed
, GROUP_CONCAT(CASE WHEN v.status <> 2 THEN v.vehicle_id END) incomplete
FROM vehicle_class vc
JOIN vehicle v
ON v.vehicle_class_id = vc.vehicle_class_id
GROUP 
BY vc.vehicle_class_id;

I need help converting in Oracle9i, DB2 and SQL Server.

Please help.

Answer 1

Here is an Oracle9i solution.
The job is done with SYS_CONNECT_BY_PATH function which needs CONNECT BY clause in the query. In order to connect rows by something VEHICLE table is “prepared”… it is filled in with curr and prev row numbers.

SELECT
  vc.vehicle_class_name,
  RTRIM(REPLACE(MAX(SYS_CONNECT_BY_PATH(v.completed,'|')) KEEP (DENSE_RANK LAST ORDER BY v.curr),'|',''),',') completed,
  RTRIM(REPLACE(MAX(SYS_CONNECT_BY_PATH(v.incomplete,'|')) KEEP (DENSE_RANK LAST ORDER BY v.curr),'|',''),',') incomplete
FROM
(SELECT
   vehicle_class_id,
   CASE WHEN status=2 THEN vehicle_id||',' END completed,
   CASE WHEN status<>2 THEN vehicle_id||',' END incomplete,
   ROW_NUMBER() OVER (PARTITION BY vehicle_class_id ORDER BY vehicle_id) curr,
   ROW_NUMBER() OVER (PARTITION BY vehicle_class_id ORDER BY vehicle_id)-1 prev
 FROM
   vehicle) v JOIN vehicle_class vc
ON v.vehicle_class_id=vc.vehicle_class_id
GROUP BY
  vc.vehicle_class_name
CONNECT BY
  v.prev=PRIOR v.curr AND v.vehicle_class_id=PRIOR v.vehicle_class_id
START WITH
  v.curr=1;