Question

I am familiar with basic queries in SQL, but I need to apply a filter and I’m not entirely sure how to go about it.

I current have this query:

var query = (from solvedPuzzle in db.SolvedPuzzles
              where solvedPuzzle.UserID == user.ID
              select solvedPuzzle);

And I want to modify the query or filter the results like this pseudocode:

for each pair (a,b) of results
  if a.PuzzleID == b.PuzzleID
     filter out a.NumberOfMoves > b.NumberOfMoves ? a : b

In case that isn’t straightforward enough, I’ll give example results of the filter

Table SolvedPuzzles:
ID   UserID    PuzzleID   NumberOfMoves
1    2         1          5
2    2         1          6   //Will be filtered out
3    2         2          7
4    3         1          8   //Will be filtered out
5    3         1          6
6    4         2          5
7    5         2          4

That is, those two will be filtered out of the results because they are by the same user and the same puzzle, but with a greater number of moves.

Answer 1

var query = (from solvedPuzzle in db.SolvedPuzzles
              where solvedPuzzle.UserID == user.ID
              order by NumberOfMoves ascending
              group solvedPuzzle by solvedPuzzle.PuzzleID into filtered
              select filtered.First());