Teradata 中的“First order by”答案

【问题标题】："First order by" in TeradataTeradata 中的“First order by”
【发布时间】：2017-04-12 07:40:58
【问题描述】：

我在将 SQL 语句从 Oracle 转换为 Teradata 时遇到问题。在 Oracle 的声明中是这样的：

SELECT ar.account_no,
MAX (ah.bal_acct) KEEP (DENSE_RANK FIRST ORDER BY ah.created_t desc) 
FROM ar
   JOIN ah ON ah.obj_id0 = ar.poid_Id0
   JOIN acc ON a.poid_id0 = ar.account_obj_Id0
WHERE acc.account_no = '1234'
AND ah.created_t <= 1434753495
GROUP BY ar.account_no

我需要在 Teradata 中做类似的声明。我尝试了

QUALIFY ROW_NUMBER() OVER( PARTITION BY max(ah.bal_acct) ORDER BY ah.created_t desc) = 1

但我一直有错误：选定的非聚合值必须是关联组的一部分。

这是我得到的：

Select ar.account_no, ah.created_t, ah.bal_acct
FROM VD_REPLICA_BRM.pi_tp_acct_ar_t ar
    JOIN VD_REPLICA_BRM.pi_tp_acct_ar_hist_T ah ON ah.obj_id0 = ar.poid_Id0
    JOIN VD_REPLICA_BRM.pi_account_t acc ON acc.poid_id0 = ar.account_obj_Id0
WHERE acc.account_no = '00003095660515'
    AND ah.created_t <= CAST('2016-10-31' AS DATE FORMAT 'YYYY-MM-DD')
QUALIFY ROW_NUMBER() OVER( PARTITION BY max(ah.bal_acct) ORDER BY ah.created_t desc) = 1
GROUP BY ar.account_no

我哪里做错了？

【问题讨论】：

ah.created_t <= date '2016-10-31'。这是日期文字的 ANSI/ISO 表示法

标签： sql oracle teradata row-number

【解决方案1】：

我不确定您是否可以使用 qualify 执行此操作。一个等效的语句是：

SELECT ar.account_no, ah.created_t, ah.bal_acct
FROM (SELECT ar.account_no, ah.created_t, ah.bal_acct,
             ROW_NUMBER() OVER (PARTITION BY ar.account_no ORDER BY ah.created_t DESC) as seqnum
      FROM ar JOIN
           ah
           ON ah.obj_id0 = ar.poid_Id0 JOIN
           acc
           ON a.poid_id0 = ar.account_obj_Id0
      WHERE acc.account_no = '1234' AND ah.created_t <= 1434753495
     ) t
WHERE seqnum = 1;

呃。您可以使用QUALIFY 执行此操作。问题是GROUP BY：

SELECT ar.account_no, ah.created_t, ah.bal_acct
FROM VD_REPLICA_BRM.pi_tp_acct_ar_t ar JOIN
     VD_REPLICA_BRM.pi_tp_acct_ar_hist_T ah
     ON ah.obj_id0 = ar.poid_Id0 JOIN
     VD_REPLICA_BRM.pi_account_t acc
     ON acc.poid_id0 = ar.account_obj_Id0
WHERE acc.account_no = '00003095660515' AND
      ah.created_t <= CAST('2016-10-31' AS DATE FORMAT 'YYYY-MM-DD')
QUALIFY ROW_NUMBER() OVER( PARTITION BY ar_account_no ORDER BY ah.created_t desc) = 1

【讨论】：