Translate SQL to lambda LINQ with GroupBy and Average

Question

I spend a few hours trying to translate simple SQL to lambda LINQ

SELECT ID, AVG(Score) FROM myTable
GROUP BY ID

Any idea?

Answer 1

The equivalent in Linq-to-Objects would be something like the below.

var results = from row in myTable
              group row by row.Id into rows 
              select new 
              {
                  Id = rows.Key,
                  AverageScore = rows.Average(row => row.Score)
              };

It's only slightly different for an ORM like entity framework. Namely, you would need to go through the data context or an appropriate DbSet/ObjectSet.