Get Distinct Entries Based On Specific Column in Entity Framework

Question

I have a SQLite table that contains every test result we\'ve run, and I\'m looking to write an entity framework query that returns only the most recent test result per project.

Answer 1

While this isn't portable, here's how this can be done using SQLite-compatable SQL and Entity Framework:

results = await _context.Results
    .FromSqlRaw("SELECT Results.* FROM (SELECT Id, ProjectId, MAX(Updated) as Updated " +
    "FROM Results GROUP BY ProjectId) as latest_results " +
    "INNER JOIN Results ON Results.Id = latest_results.Id")
    .Include(x => x.Project) //not required for question but useful
    .OrderBy(x => x.Project.Name)
    .AsNoTracking()
    .ToListAsync();

If someone has a way to do this in pure LINQ/EF, but still perform the query server-side, I'll happily mark that as the answer, since this is dependent on the exact SQL dialect used.