Teradata SQL CASE Statement with multiple conditions - sql

Question

I have the below SQL query -
select distinct HospitalAcctID,
AdmitDate,
DischargeDate,
PatMRN,
Pat_id,
ICD,
MedCenter,
(case when SeqCount =1 and AdmitDate > '06/01/2013' and AdmitDate < '06/01/2018' then 1 else null end ) Firstdiag
from
(
select distinct acct.HSP_ACCOUNT_ID as HospitalAcctID,
cast(acct.ADM_DATE_TIME as date format 'mm/dd/yyyy') as AdmitDate,
cast(acct.DISCH_DATE_TIME as date format 'mm/dd/yyyy') as DischargeDate,
pat.pat_mrn_id as PatMRN,
pat.pat_id as Pat_id,
REF_BILL_CODE as ICD,
grp7.NAME AS MedCenter,
row_number() over (partition by PatMRN order by AdmitDate) as SeqCount
from acct
inner join pat on pat.pat_id = acct.pat_id
inner join hspenc on hspenc.CSN_ID = acct.CSN_ID
inner join dx on acct.ACCOUNT_ID = dx.ACCOUNT_ID and line = 1
inner join edg on dx.DX_ID = edg.DX_ID
inner join loc on loc.LOC_ID = acct.LOC_ID
inner join grp7 ON loc.RPT_GRP_SEVEN = grp7.RPT_GRP_SEVEN
where
grp7.NAME = 'SMC AREA'
and ADMIT_CONF_STAT_C in ('1','4')
and (edg. REF_BILL_CODE in ('431',
'431')
)
and ADT_PAT_CLASS_C in ('1204','12113')
order by AdmitDate;
)Admit
But I am getting the below syntax error -
Syntax error, expected something like an 'EXCEPT' keyword, 'UNION' Keyword or a 'MINUS' keyword between 'AdmitDate' and ','
In the outer select statement, I am trying to get the min (first ) date when the was first diagnosed. I also want to get only the patients who were diagnosed between 6/2013 to 6/2018 which is why I have the CASE statement. But the CASE statement is giving me error.

Answer 1

As #BarbarosÖzhan already wrote, remove the last line order by AdmitDate; in the Derived Table.
But there's no need for ROW_NUMBER:
select distinct acct.HSP_ACCOUNT_ID as HospitalAcctID,
cast(acct.ADM_DATE_TIME as date format 'mm/dd/yyyy') as AdmitDate,
cast(acct.DISCH_DATE_TIME as date format 'mm/dd/yyyy') as DischargeDate,
pat.pat_mrn_id as PatMRN,
pat.pat_id as Pat_id,
REF_BILL_CODE as ICD,
grp7.NAME AS MedCenter,
case when -- current rows is first row
min(AdmitDate)
over (partition by PatMRN) = AdminDate
-- current row within date range
and AdminDate >= DATE '2013-06-01' and AdmitDate < DATE '2018-06-01'
then 1
else null
end as Firstdiag
from acct
inner join pat on pat.pat_id = acct.pat_id
inner join hspenc on hspenc.CSN_ID = acct.CSN_ID
inner join dx on acct.ACCOUNT_ID = dx.ACCOUNT_ID and line = 1
inner join edg on dx.DX_ID = edg.DX_ID
inner join loc on loc.LOC_ID = acct.LOC_ID
inner join grp7 ON loc.RPT_GRP_SEVEN = grp7.RPT_GRP_SEVEN
where
grp7.NAME = 'SMC AREA'
and ADMIT_CONF_STAT_C in ('1','4')
and (edg. REF_BILL_CODE in ('431',
'431')
)
and ADT_PAT_CLASS_C in ('1204','12113')
order by AdmitDate;
I also switched to a Standard SQL date literal DATE '2013-06-01' instead of '06/01/2013'. There's only one possible format for the former (DATE 'YYYY-MM-DD') while the latter depends on the FORMAT of the base column and might fail when it changes (of course not in your query, because you defined it in the CAST).