Max / Where子句

Question

我是sql的新手并拥有以下查询。有多行，因为在每个月的最后一天添加了一个新行。我想要做的是选择具有最新accounting_dt的记录。我一直试图在accounting_dt字段上使用max，但一直都会出错。任何帮助将不胜感激。如果有更好的方法来编写此查询，我也很感谢这些评论。正如我之前所说，我是新手，我希望学习正确的方法来做这些事情。再次感谢你的帮助。

  SELECT 
    pa.BUSINESS_UNIT,
    pdr.DEPTID,
    pa.IN_SERVICE_DT,
    pa.ASSET_ID,
    pa.DESCR,
    pb.LIFE,
    pb.METHOD,
    pdr.COST,
    pdr.DEPR,
    pdr.depr_ytd,
    pdl.accounting_dt

    from PS_ASSET pa,
    PS_BOOK pb,
    PS_DEPR_RPT pdr,
    PS_DIST_LN pdl

    where pa.BUSINESS_UNIT = 'A0056'
    and pa.ASSET_ID = '000000000003'
    and pb.BOOK = 'PERFORM'
    and pdr.book = 'PERFORM'
    and pdl.book = 'PERFORM'
    and pdr.FISCAL_YEAR = '2014'
    and pdr.ACCOUNTING_PERIOD = '12'
    and pb.ASSET_ID= pa.ASSET_ID and pb.BUSINESS_UNIT = pa.BUSINESS_UNIT
    and pdr.ASSET_ID= pa.ASSET_ID and pdr.BUSINESS_UNIT = pa.BUSINESS_UNIT
    and pdl.ASSET_ID= pa.ASSET_ID and pdl.BUSINESS_UNIT = pa.BUSINESS_UNIT
    and pdl.distribution_type = 'DE'

结果：

   BU    DEPTID  INSERVDT     IDNO            DSCR     LIFE   METH      COST      DEPREC
         ACCUMDP  ACCT_DT

A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  31-JAN-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  28-FEB-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  31-MAR-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  30-APR-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  31-JUL-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  31-JUL-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  30-JUN-14
A0056       01-JAN-14   000000000003    Test    72  SL  500 7.36    659.75  30-JUN-14

Answer 1

您应该了解明确的join语法。它不仅使查询更具可读性，而且是更强大的符号。

我猜你想要每个BU的最新记录。您可以使用row_number()解决问题。以下是如何执行此操作的示例：

with t as (
      <your query goes here>
     )
select t.*
from (select t.*,
             row_number() over (partition by bu order by accounting_dt desc) as seqnum
      from t
     ) t
where seqnum = 1;