An error "Could not find symbol: n.hospadmissiontime" occurs when executing the statement below. I'll add a full sql script because this is executed in a procedure. Running this outside of a procedure does not seem to result in an issue.

SELECT n.*
FROM #tmp_admission_to_update tu
join tmp_newvals n on n.admissionid = tu.patientid
join tmp_oldvals o on o.admissionid = tu.patientid
where tu.in_tbl and
(
n.hospadmissiontime is distinct from o.hospadmissiontime or
n.origin is distinct from o.origin or
n.hospital is distinct from o.hospital or
n.gender is distinct from o.gender or
n.nationality is distinct from o.nationality or
n.postalcode is distinct from o.postalcode or
n.country is distinct from o.country or
n.hospitaldischargetime is distinct from o.hospitaldischargetime or
n.destination is distinct from o.destination or
n.warddischarge is distinct from o.warddischarge or
(n.foto is null and o.foto is not null)
)