Question

Suppose we have the following table data:

ID   parent    stage     submitted
1      1         1           1
2      1         2           1
3      1         3           0
4      1         4           0
5      5         1           1
6      5         2           1
7      5         3           1
8      5         4           1

As you can see we have 2 groups (that have the same parent). I want to select the latter stage that is submitted. In the above example i want to select the ID`s 2 and 8. I am completely lost so if anyone can help it will be appreciated a lot. 🙂

Answer 1

SELECT T.ID, T.PARENT, T.STAGE 
from
   T, 
   (
      select PARENT, MAX( STAGE) MAX_STAGE 
      from T
      where SUBMITTED = 1
      GROUP BY PARENT 
   ) M
where 
   T.STAGE = M.MAX_STAGE 
   AND T.PARENT = M.PARENT

Explanation:
First, isolate the max stage for each group with submitted = 1 (the inner select).
Then, join the result with the real table, to filter out the records with no max stage.