具有多个条件的Teradata SQL CASE语句

Question

我有以下SQL查询-

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

但是我遇到了以下语法错误-语法错误，预期是“ AdmitDate”和“，”之间的“ EXCEPT”关键字，“ UNION”关键字或“ MINUS”关键字

在外部的select语句中，我试图获取首次诊断出的最小（第一个）日期。 我也只想获取在6/2013到6/2018之间被诊断出的患者，这就是为什么要使用CASE语句。 但是CASE语句给了我错误。

Answer 1

正如@BarbarosÖzhan所写，删除order by AdmitDate;的最后一行order by AdmitDate; 在派生表中。

但是不需要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;

我还切换到了标准SQL日期文字DATE '2013-06-01'而不是'06/01/2013' 。 前者只有一种可能的格式（ DATE 'YYYY-MM-DD' ），而后者则取决于基本列的FORMAT，并且在其更改时可能会失败（当然不是在您的查询中，因为您在CAST中定义了它） ）。