Question

I have this table and I would like to do the following :

idstep   idproject   beg_date  end_date
   1        1
   2        1
   3        1
   4        1
   1        2
   2        2
   3        2
   4        2
   5        2
   1        3
   2        3
   3        3

Retrieve the Maximum steps for each project without using “GROUP BY”

Using the GROUP BY clause, I get the result that I want which is the following:

  SELECT MAX(idstep), idproject 
    FROM mytable
GROUP BY idproject;

Result:

    idstep     idproject
    4            1
    5            2
    3            3

Please, can anyone here can help me out with this issue?

Answer 1

I agree that this makes more sense to use GROUP BY for this particular case, but this should work:

SELECT t.project, t.step
FROM YourTable t
  LEFT JOIN YourTable t2 on t.step < t2.step and t.project = t2.project
where t2.step IS NULL

And here is the Fiddle.

You could also use NOT EXISTS (feel like I’ve been using it all night), although I personally prefer the LEFT JOIN / NULL approach:

SELECT t.project, t.step
FROM YourTable t
WHERE NOT EXISTS (
  SELECT *
  FROM YourTable t2 
  WHERE t.step < t2.step 
    AND t.project = t2.project
)

More fiddle: http://www.sqlfiddle.com/#!2/ebbc2/1

Good luck.