Question

我在DB2服务器上运行了一个相当大的查询。在该查询中，我有一个包含20个选项的case语句。这个案例很有效，直到我尝试在每个when子句中放置一个子查询。然后它给了我一个错误，我们不确定它发生在哪里。

Select SCDATA.SCCLNT.CCLNT,
  (Select SCDATA.SCCLNT.CNAME From SCDATA.SCCLNT
  Where SCDATA.SCCLNT.CLTGRP Like '231043' Fetch First
    1 Rows Only) As ClientName,
  CONCAT(TRIM(SCDATA.SCCLNT.CADD1), SCDATA.SCCLNT.CADD2) As Address1,
  CONCAT(TRIM(SCDATA.SCCLNT.CCITY), CONCAT(', ',
  CONCAT(TRIM(SCDATA.SCCLNT.CSTATE), CONCAT('  ',             
TRIM(SCDATA.SCCLNT.CZIP)))))
  As Address2,
  SCDATA.SCCLNT.CLTGRP As Group,
  CONCAT((Select     
VARCHAR_FORMAT(Min(TIMESTAMP_FORMAT(Cast(SCDATA.SCACCT.GPLDAT
    As Char(10)), 'YYYYMMDD')), 'MM/DD/YYYY') From SCDATA.SCACCT
  Where SCDATA.SCACCT.GPLDAT Between 20170401 and 20170501), CONCAT(' -     ',
  (Select VARCHAR_FORMAT(Max(TIMESTAMP_FORMAT(Cast(SCDATA.SCACCT.GPLDAT     As
    Char(10)), 'YYYYMMDD')), 'MM/DD/YYYY') From SCDATA.SCACCT
  Where SCDATA.SCACCT.GPLDAT Between 20170401 and 20170501))) As     dateRange,
  SCDATA.SCACCT.GCLNT,
  SCDATA.SCACCT.GPLACE,
  SCDATA.SCACCT.GPLDAT,
  SCDATA.SCACCT.GACCT# As GACCTnum,
  CONCAT(TRIM(SCDATA.SCACCT.GLAST), CONCAT(', ',     TRIM(SCDATA.SCACCT.GFIRST))) As
  Debtor,
  ( SCDATA.SCACCT.GPRI +  SCDATA.SCACCT.GINT) as Balance,
   SCDATA.SCACCT.Gdebt#,
CASE
   WHEN GDC20 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC20     FETCH TOP 1 ROWS)
   WHEN GDC19 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC19 FETCH TOP 1 ROWS)
   WHEN GDC18 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC18 FETCH TOP 1 ROWS)
   WHEN GDC17 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC17     FETCH TOP 1 ROWS)
   WHEN GDC16 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC16 FETCH TOP 1 ROWS)
   WHEN GDC15 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC15 FETCH TOP 1 ROWS)
   WHEN GDC14 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC14 FETCH TOP 1 ROWS)
   WHEN GDC13 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC13 FETCH TOP 1 ROWS)
   WHEN GDC12 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC12 FETCH TOP 1 ROWS)
   WHEN GDC11 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC11 FETCH TOP 1 ROWS)
   WHEN GDC10 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC10 FETCH TOP 1 ROWS)
   WHEN GDC09 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC09 FETCH TOP 1 ROWS)
   WHEN GDC08 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC08 FETCH TOP 1 ROWS) 
   WHEN GDC07 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC07 FETCH TOP 1 ROWS) 
   WHEN GDC06 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC06 FETCH TOP 1 ROWS) 
   WHEN GDC05 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC05 FETCH TOP 1 ROWS) 
   WHEN GDC04 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC04 FETCH TOP 1 ROWS) 
   WHEN GDC03 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC03 FETCH TOP 1 ROWS) 
   WHEN GDC02 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC02 FETCH TOP 1 ROWS) 
   WHEN GDC01 !='' THEN  (Select SDDESC from SC0016 where SDCODE=GDC01 FETCH TOP 1 ROWS) 
   ELSE 'xx'
END as Description


From SCDATA.SCCLNT
  inner Join SCDATA.SCACCT On SCDATA.SCACCT.GCLNT = SCDATA.SCCLNT.CCLNT     And
    SCDATA.SCACCT.GPLDAT Between 20170401 and 20170501
Where SCDATA.SCCLNT.CLTGRP Like '231043'
Group By SCDATA.SCCLNT.CCLNT,
  SCDATA.SCCLNT.CLTGRP,
  SCDATA.SCCLNT.CNAME,
  SCDATA.SCCLNT.CADD1,
  SCDATA.SCCLNT.CADD2,
  SCDATA.SCCLNT.CCITY,
  SCDATA.SCCLNT.CSTATE,
  SCDATA.SCCLNT.CZIP,
  SCDATA.SCACCT.GFIRST,
  SCDATA.SCACCT.GLAST,
  SCDATA.SCACCT.GCLNT,
  SCDATA.SCACCT.GPLACE,
  SCDATA.SCACCT.GPLDAT,
  SCDATA.SCACCT.GACCT#,
SCDATA.SCACCT.gpri,
SCDATA.SCACCT.GINT,
SCDATA.SCACCT.GDEBT#,
GDC20,
GDC19,
GDC18,
GDC17,
GDC16,
GDC15,
GDC14,
GDC13,
GDC12,
GDC11,
GDC10,
GDC09,
GDC08,
GDC07,
GDC06,
GDC05,
GDC04,
GDC03,
GDC02,
GDC01

此查询背后的目的是获取最高排名的描述代码以便在查询结果中显示，但是程序是为了随着时间的推移添加描述而构建的，所以我需要从20倒数到1来查找最近的用过的代码。代码是一个简单的2字符组合，对应于我需要提取信息的另一个表。

问题是如何在DB2中重新设计case语句以从SC0016表中提取我需要的单个值？

由于

Answer 1

事实证明，解决方案是将select case放在join语句中。所以在选择部分我会列出我想要的字段，SDDESC，以及我想要的连接左侧连接SC0016在SDCODE = 案例当GDC20！=＆＃39;＆＃39;那么GDC20 ......结束

这将允许我根据第一个表中填充最高的列连接每一行。不是很规范，但我没有写数据库:)这很有效。

如何在DB2选择案例中包含来自不同表的select

1 个答案: