Question

I Have a table which holds date but I need to know the latest date where a condition is true per location, only issue is once I add a column called ‘notes’ it breaks the query and returns too many rows, current query is …

SELECT
        Location,
        MAX(date) AS date,
        type,
        notes
  FROM NotesTable a
 INNER JOIN Location b on a.LocationID = b.LocationID
 INNER JOIN Type c on a.typeid = c.typeid
 WHERE typeid <> 8
 GROUP BY Location, type, notes

If I comment out the notes column then it works fine but as soon as I add that to the grouping it then returns more rows than required.

Have tried using a subquery but still cant get it working, subquery below

SELECT
        r.location,
        r.date,
        r.type,
        t.notes
  FROM (SELECT Location, MAX(date), type
          FROM NotesTable a INNER JOIN Location b on a.LocationID = b.LocationID
         INNER JOIN Type c on a.typeid = c.typeid
         WHERE typeid <> 8
         GROUP BY location,type
        ) r
INNER JOIN NotesTable t ON t.date = r.date

Anyone got any other suggestions?

Answer 1

select * from
(
     SELECT Location,Date, Type, Notes, Row_Number() Over (Partition By Location, Type order by date desc) RN 
     FROM
          NotesTable a
           INNER JOIN Location b on a.LocationID = b.LocationID
           INNER JOIN Type c on a.typeid = c.typeid
      WHERE typeid <> 8
) v
WHERE rn = 1