Order dates with multiple columns (some containing nulls) - tsql

Question

I have 4 dates (derived from separate subqueries) as in below but I want to find the MAX and MIN dates of the values returned.
I've tried using CASE which will not work with the null values.
Also tried using COALESCE in the subs to get values and then using CTE but this also didn't work.
(The overall query is to find customers with no -9 in a1.id)
There's a lot of help in SO but nothing that I can get to fit this purpose.
Any help would be greatly appreciated.
DESIRED COLUMNS
PAT_ID Date1 Date2 Date3 Date4 MAX MIN
1 01/04/2015 25/12/2000 02/02/2011 01/04/2015 25/12/2000
2 05/08/1950 11/11/2011 11/11/2011 05/08/1950
3 04/01/1958 04/01/1958 04/01/1958
4 01/01/1900 01/01/1900
5 15/08/2017 07/07/1967 15/08/2017 07/07/1967
select distinct
ca1.id AS PT_ID,
(select Top 1 s1z.appointmen ApptDate
from schl_booking_appoin s1z
LEFT OUTER JOIN core_patient c3z ON s1z.patient = c3z.id
LEFT OUTER JOIN schl_appt_history_s s2z ON s1z.currentsta = s2z.id
LEFT OUTER JOIN applookup_instance a2z ON s2z.lkp_status = a2z.id
where (c3z.id = ca1.id and a2z.text not like '%cancelled%' and s1z.appointmen
> :SYS_DATE_TIME)
order by s1z.appointmen asc ) AS Date1,
(select Top 1
s1q.appointmen ApptDate
from schl_booking_appoin s1q
LEFT OUTER JOIN core_patient c3q ON s1q.patient = c3q.id
LEFT OUTER JOIN schl_appt_history_s s2q ON s1q.currentsta = s2q.id
LEFT OUTER JOIN applookup_instance a2q ON s2q.lkp_status = a2q.id
where (c3q.id = ca1.id and a2q.text not like '%cancelled%' and s1q.appointmen
< :SYS_DATE_TIME)
order by s1q.appointmen desc ) AS Date2,
(select top 1
CONVERT (VARCHAR(20),c2y.admissiond, 103) AdmissionDate
from core_admissiondetai c2y
LEFT OUTER JOIN core_pas_event c3y ON c2y.pasevent = c3y.id
LEFT OUTER JOIN core_patient c4y ON c3y.patient = c4y.id
where (c4y.id = ca1.id)
order by c2y.admissiond desc ) AS Date3,
(select top 1
CONVERT(VARCHAR(20),c5k.arrivaldat,103) ArrivalDate
from core_emergencyatten c5k
LEFT OUTER JOIN core_patient c6k ON c5k.patient = c6k.id
where (c6k.id = ca1.id)
order by c5k.arrivaldat desc ) AS Date4
from core_patient ca1
LEFT OUTER JOIN core_patient_c_identifi ca2 ON ca1.id = ca2.id
LEFT OUTER JOIN applookup_instance aa2 ON ca1.lkp_sex = aa2.id
LEFT OUTER JOIN applookup_instance aa1 ON ca2.lkp_c_ty = aa1.id
LEFT OUTER JOIN applookup_instance ab1 ON ca1.lkp_overseascl = ab1.id
LEFT OUTER JOIN core_organisation cx4 ON ca1.practice = cx4.id
WHERE ca1.id IN
(
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where ((ca2.merged = 0 or ca2.merged is null)
and aa1.id = -2404) )
AND ca1.id NOT IN (
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where (c1.namesurname not like '%XXTEST%'
and c1.namesurname not like '%ZZ%'
and a1.id = -9)
)

Answer 1

try this version. Your old query acts as a subquery and introducing a new column definition to get the Max Date.
SELECT PT_ID,
(
SELECT Max(v)
FROM (VALUES (Date1), (Date2), (Date3),(Date4)) AS value(v)
) as [MaxDate]
FROM
(
select distinct
ca1.id AS PT_ID,
(select Top 1 s1z.appointmen ApptDate
from schl_booking_appoin s1z
LEFT OUTER JOIN core_patient c3z ON s1z.patient = c3z.id
LEFT OUTER JOIN schl_appt_history_s s2z ON s1z.currentsta = s2z.id
LEFT OUTER JOIN applookup_instance a2z ON s2z.lkp_status = a2z.id
where (c3z.id = ca1.id and a2z.text not like '%cancelled%' and s1z.appointmen
> :SYS_DATE_TIME)
order by s1z.appointmen asc ) AS Date1,
(select Top 1
s1q.appointmen ApptDate
from schl_booking_appoin s1q
LEFT OUTER JOIN core_patient c3q ON s1q.patient = c3q.id
LEFT OUTER JOIN schl_appt_history_s s2q ON s1q.currentsta = s2q.id
LEFT OUTER JOIN applookup_instance a2q ON s2q.lkp_status = a2q.id
where (c3q.id = ca1.id and a2q.text not like '%cancelled%' and s1q.appointmen
< :SYS_DATE_TIME)
order by s1q.appointmen desc ) AS Date2,
(select top 1
CONVERT (VARCHAR(20),c2y.admissiond, 103) AdmissionDate
from core_admissiondetai c2y
LEFT OUTER JOIN core_pas_event c3y ON c2y.pasevent = c3y.id
LEFT OUTER JOIN core_patient c4y ON c3y.patient = c4y.id
where (c4y.id = ca1.id)
order by c2y.admissiond desc ) AS Date3,
(select top 1
CONVERT(VARCHAR(20),c5k.arrivaldat,103) ArrivalDate
from core_emergencyatten c5k
LEFT OUTER JOIN core_patient c6k ON c5k.patient = c6k.id
where (c6k.id = ca1.id)
order by c5k.arrivaldat desc ) AS Date4
from core_patient ca1
LEFT OUTER JOIN core_patient_c_identifi ca2 ON ca1.id = ca2.id
LEFT OUTER JOIN applookup_instance aa2 ON ca1.lkp_sex = aa2.id
LEFT OUTER JOIN applookup_instance aa1 ON ca2.lkp_c_ty = aa1.id
LEFT OUTER JOIN applookup_instance ab1 ON ca1.lkp_overseascl = ab1.id
LEFT OUTER JOIN core_organisation cx4 ON ca1.practice = cx4.id
WHERE ca1.id IN
(
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where ((ca2.merged = 0 or ca2.merged is null)
and aa1.id = -2404) )
AND ca1.id NOT IN (
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where (c1.namesurname not like '%XXTEST%'
and c1.namesurname not like '%ZZ%'
and a1.id = -9)
)
)Sub

Answer 2

You could do the following:
make your query into a CTE;
flatten the data so it becomes a list of PT_IDs and dates;
from this flattened data find the maximum and minimum date per PT_ID;
bring this all back together in one final query.
This is a stab at doing all of the above:
WITH x AS (
select distinct
ca1.id AS PT_ID,
(select Top 1 s1z.appointmen ApptDate
from schl_booking_appoin s1z
LEFT OUTER JOIN core_patient c3z ON s1z.patient = c3z.id
LEFT OUTER JOIN schl_appt_history_s s2z ON s1z.currentsta = s2z.id
LEFT OUTER JOIN applookup_instance a2z ON s2z.lkp_status = a2z.id
where (c3z.id = ca1.id and a2z.text not like '%cancelled%' and s1z.appointmen
> :SYS_DATE_TIME)
order by s1z.appointmen asc ) AS Date1,
(select Top 1
s1q.appointmen ApptDate
from schl_booking_appoin s1q
LEFT OUTER JOIN core_patient c3q ON s1q.patient = c3q.id
LEFT OUTER JOIN schl_appt_history_s s2q ON s1q.currentsta = s2q.id
LEFT OUTER JOIN applookup_instance a2q ON s2q.lkp_status = a2q.id
where (c3q.id = ca1.id and a2q.text not like '%cancelled%' and s1q.appointmen
< :SYS_DATE_TIME)
order by s1q.appointmen desc ) AS Date2,
(select top 1
CONVERT (VARCHAR(20),c2y.admissiond, 103) AdmissionDate
from core_admissiondetai c2y
LEFT OUTER JOIN core_pas_event c3y ON c2y.pasevent = c3y.id
LEFT OUTER JOIN core_patient c4y ON c3y.patient = c4y.id
where (c4y.id = ca1.id)
order by c2y.admissiond desc ) AS Date3,
(select top 1
CONVERT(VARCHAR(20),c5k.arrivaldat,103) ArrivalDate
from core_emergencyatten c5k
LEFT OUTER JOIN core_patient c6k ON c5k.patient = c6k.id
where (c6k.id = ca1.id)
order by c5k.arrivaldat desc ) AS Date4
from core_patient ca1
LEFT OUTER JOIN core_patient_c_identifi ca2 ON ca1.id = ca2.id
LEFT OUTER JOIN applookup_instance aa2 ON ca1.lkp_sex = aa2.id
LEFT OUTER JOIN applookup_instance aa1 ON ca2.lkp_c_ty = aa1.id
LEFT OUTER JOIN applookup_instance ab1 ON ca1.lkp_overseascl = ab1.id
LEFT OUTER JOIN core_organisation cx4 ON ca1.practice = cx4.id
WHERE ca1.id IN
(
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where ((ca2.merged = 0 or ca2.merged is null)
and aa1.id = -2404) )
AND ca1.id NOT IN (
select c1.id core_patient_c1_id
from core_patient c1
LEFT OUTER JOIN core_patient_c_identifi c2 ON c1.id = c2.id
LEFT OUTER JOIN applookup_instance a1 ON c2.lkp_c_ty = a1.id
where (c1.namesurname not like '%XXTEST%'
and c1.namesurname not like '%ZZ%'
and a1.id = -9)
)),
y AS (
SELECT PT_ID, Date1 AS [Date] FROM x WHERE Date1 IS NOT NULL
UNION ALL
SELECT PT_ID, Date2 AS [Date] FROM x WHERE Date2 IS NOT NULL
UNION ALL
SELECT PT_ID, Date3 AS [Date] FROM x WHERE Date3 IS NOT NULL
UNION ALL
SELECT PT_ID, Date4 AS [Date] FROM x WHERE Date4 IS NOT NULL),
z AS (
SELECT
PT_ID,
MIN([Date]) AS Min_Date,
MAX([Date]) AS Max_Date
FROM
y
GROUP BY
PT_ID)
SELECT
x.PT_ID,
x.Date1,
x.Date2,
x.Date3,
x.Date4,
z.Min_Date,
z.Max_Date
FROM
x
LEFT JOIN z ON z.PT_ID = x.PT_ID;