Question

我有两个选择查询，它们返回结果集以下。

ResultSet1：

FIELD_NAME      DISPLAY        MASK         DEFAULTVALUE
LOANTYPE        1           Test LoanType       2
PREAPPROVAL     1           Test Preapproval    2

ResultSet2：

 FIELDNAME       DISPLAY    MASK                DEFAULTVALUE
  LOANTYPE                  NA                  NA
  INTEREST                  NA                  NA
  HOMETYPE                  NA                  NA
  PREAPPROVAL               NA                  NA
  PURCHASERTYPE             NA                  NA
  PURPOSE                   NA                  NA
  PREAPPROVAL               NA                  NA

我想得到如下结果。任何帮助将不胜感激。

    FIELD_NAME      DISPLAY        MASK         DEFAULTVALUE
  LOANTYPE           1          Test LoanType       2
  PREAPPROVAL        1          Test Preapproval    2
  INTEREST                        NA                NA
  HOMETYPE                        NA                NA
  PREAPPROVAL                     NA                NA
  PURCHASERTYPE                   NA                NA
  PURPOSE                         NA                NA
  PREAPPROVAL                     NA                NA

这里需要删除重复的LOANTYPE和PREAPPROVAL值。我尝试了两个CTE，并进行了正确的联接。但这没有给出预期的结果。

Answer 1

您可以尝试使用窗口函数row_number（）

 with cte as
(
SELECT *,row_number() over(partition by FIELD_NAME order by DISPLAY desc,MASK desc,DEFAULTVALUE desc) rn
   FROM (
   Query1 
   UNION 
   Query2
     ) t
) select * from cte where rn=1

Answer 2

您应该可以使用外部联接和coalesce()：

select r2.field_name,
       coalesce(r1.display, r2.display) as display,
       coalesce(r1.mask, r2.mask) as mask,
       coalesce(r1.defaultvalue, r2.defaultvalue) as defaultvalue
 from resultset2 r2 left join
      resultset1 r1
      on r1.field_name = r2.field_name;

Answer 3

您可以在下面使用左联接和CASE WHEN尝试

如果table2值为空，则可以使用Coalesce（）函数代替CASE

select 
   a.FIELD_NAME, 
   case when a.DISPLAY='NA' then b.display else a.display end as DISPLAY,
   case when a.MASK='NA' then b.Mask else a.mask end as MASK,         
   case when a.DEFAULTVALUE='NA' then b.defaultvalue else a.defaultvalue end as Defaultvalue
 from resultset2 a left join resultset1 b 
 on a.loantype=b.loadtype

如何从SQL Server中的两个选择查询中消除重复数据

3 个答案: