1589 patients' first_careunit is different from last_careunit in mimic_icu.icustays but had the only stay_id.

[zyh1996007]

I found that 1589 patients' first_careunit is different from last_careunit in mimic IV_"mimic_icu"."icustays" but had the only stay_id.
what happened? thank you

create MATERIALIZED view a1 as
①SELECT b3.subject_id,b3.hadm_id,b4.stay_id,b3.admittime,b4.intime,b4.outtime,b3.dischtime,b3.deathtime,b4.los,b4.first_careunit,b4.last_careunit from
(select subject_id,hadm_id,admittime,dischtime,deathtime from admissions INNER join (select subject_id,count (distinct hadm_id) from admissions group by (subject_id ) having count (distinct hadm_id)=1) as b1 using (subject_id)) as b3
INNER join
(select subject_id,hadm_id,stay_id,intime,outtime,first_careunit,last_careunit,los from "mimic_icu"."icustays" INNER join (select subject_id from "mimic_icu"."icustays" GROUP BY(subject_id) having count(DISTINCT stay_id)=1 ) as b2 using (subject_id) ORDER BY subject_id) as b4 using (hadm_id)
ORDER BY subject_id;

②SELECT * from a1 where first_careunit<>last_careunit