Efficiently Include Column not in Group By of SQL Query

Question

Given

Table A

Id   INTEGER
Name VARCHAR(50)

Table B

Id   INTEGER
FkId INTEGER  ;          


        

Answer 1

select t3.Name, t3.FkId, t3.countedFkId from (a t1 
  join (select t2.FkId, count(FkId) as countedFkId from b t2 group by t2.FkId) 
  on t1.Id = t2.FkId) t3;

Answer 2

Did you try adding the field to the group by?

SELECT FkId, COUNT(FkId), a.Name
FROM B b
INNER JOIN A a ON a.Id=b.FkId
GROUP BY FkId,a.Name

Answer 3

You can try something like this:

   ;WITH GroupedData AS
   (
       SELECT FkId, COUNT(FkId) As FkCount
       FROM B 
       GROUP BY FkId
   ) 
   SELECT gd.*, a.Name
   FROM GroupedData gd
   INNER JOIN dbo.A ON gd.FkId = A.FkId

Create a CTE (Common Table Expression) to handle the grouping/counting on your Table B, and then join that result (one row per FkId) to Table A and grab some more columns from Table A into your final result set.