Teradata SQL CASE Statement with multiple conditions

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).