Confirmation

Group by

FQL allows you to group results with a group by clause, which is quite similar to an SQL group by. But there are differences. However, the basic syntax of the group by clause is the same.

  from Patient
  group by name.family
  select family

As you can see, the group by precedes the select statement, to allow concatenation or pipelining of results.

Aggregation

Aggregation functions already exists in FHIRpath, which is the inner language used by FQL to get values. And so a typical group function like `count()' can be used on groups, like this:

from Patient
group by name.family
select family, group.count()

But because we are working with tree structured data, many more options open up, like doing a count over a full FHIRpath expression.

from Patient
group by name.family
select
  family,
  group.name.given.count()