Question

When I try to use the following SELECT statement:

SELECT [lots of columns] 
FROM Client, Customer, Document, Group
WHERE [some conditions]
GROUP BY Group.id

SQL Server complains that the columns I selected are not part of the GROUP BY statement nor an aggregate function. Am I using GROUP BY wrong? What should I be using instead?

Answer 1

To return all single occurences of a group by field, together with associated field values, write a query like:

select group_field,
       max(other_field1),
       max(other_field2),
...
from mytable1
join mytable2 on ... 
group by group_field
having count(*) = 1;