FQL

FhirPath

FhirPath is a fundamental part of FQL. As you might have read: FQL is a combination of the power of SQL, JSON and FhirPath. But it's FhirPath that get's you the values out of your data.

When ever you select fields in FQL, you do that with FhirPath. In the following statement, you see with gradually increasing complexity, how values are extracted from a resource:

from Patient
select
    birthDate,
    name[0].given[0],
    LastName: name[0].family
    phone: telecom.where(system = 'phone').value

    identifier { system, value }

The FhirPath expressions in the above FQL query are:

birthDate
name[0].given[0]
name[0].family
telecom.where(system = 'phone').value

And for the last line, there are actually three:

identifier
system
value

In the following sections of this documentation, we'll describe how you can FhirPath works and how you can apply it.