比较oracle中的多行多列

如何解决比较oracle中的多行多列

我在 Oracle SQL 中工作，假设我有一个这样的表，其中包含项目各个阶段的开始日期和完成日期。

项目编号	阶段	开始日期	完成日期
PROJ_001	1	12-MAR-21	12-MAR-21
PROJ_001	2	14-MAR-21	14-MAR-21
PROJ_001	3	15-MAR-21	15-MAR-21
PROJ_001	4	18-MAR-21	18-MAR-21
PROJ_002	1	16-MAR-21	18-MAR-21
PROJ_002	2	17-MAR-21	19-MAR-21
PROJ_002	3	19-MAR-21	19-MAR-21
PROJ_002	4	21-MAR-21	23-MAR-21

我需要将输出如下表。 对于阶段级输出，需要比较完成日期和开始日期 对于项目级别，需要检查项目的最后阶段（即阶段 4）

项目编号	阶段	开始日期	完成日期	输出 1	输出2项目级别
PROJ_001	1	12-MAR-21	12-MAR-21	准时	准时
PROJ_001	2	14-MAR-21	14-MAR-21	准时	准时
PROJ_001	3	15-MAR-21	15-MAR-21	准时	准时
PROJ_001	4	18-MAR-21	18-MAR-21	准时	准时
PROJ_002	1	16-MAR-21	18-MAR-21	延迟	延迟
PROJ_002	2	17-MAR-21	19-MAR-21	延迟	延迟
PROJ_002	3	19-MAR-21	19-MAR-21	准时	延迟
PROJ_002	4	21-MAR-21	23-MAR-21	延迟	延迟

有人可以帮我吗？

解决方法

您可以编写 2 个查询，{Q1} 返回“输出 1”所需的值，{2} 为您提供“输出 2”的值。一旦您看到这些查询产生正确的结果，将它们连接在一起。示例参见 DBfiddle。

查询 1（“阶段级别”）

select 
  projectno,stages,startdate,completiondate,case
    when startdate = completiondate then 'on time'
    else 'delayed'
  end output_1
from projects;

查询 2（“项目级别”）

-- look at the last stage (only).  CASE may need tweaking
select 
  projectno,case 
    when max( startdate ) = max( completiondate ) then 'on time'
    else 'delayed'
  end output_2  
from projects
group by projectno
;

加入

select Q1.*,Q2.output_2
from (
  select 
    projectno,case
      when startdate = completiondate then 'on time'
      else 'delayed'
    end output_1
  from projects
) Q1 join (
  select 
    projectno,case 
      when max( startdate ) = max( completiondate ) then 'on time'
      else 'delayed'
    end output_2  
  from projects
  group by projectno
) Q2 on Q1.projectno = Q2.projectno 
order by Q1.projectno,Q1.startdate
;

-- result
PROJECTNO   STAGES  STARTDATE   COMPLETIONDATE  OUTPUT_1  OUTPUT_2
PROJ_001    1      12-MAR-21    12-MAR-21       on time   on time
PROJ_001    2      14-MAR-21    14-MAR-21       on time   on time
PROJ_001    3      15-MAR-21    15-MAR-21       on time   on time
PROJ_001    4      18-MAR-21    18-MAR-21       on time   on time
PROJ_002    1      16-MAR-21    18-MAR-21       delayed   delayed
PROJ_002    2      17-MAR-21    19-MAR-21       delayed   delayed
PROJ_002    3      19-MAR-21    19-MAR-21       on time   delayed
PROJ_002    4      21-MAR-21    23-MAR-21       delayed   delayed

附录

（采纳@Thorsten Kettner 的建议：）您还可以以解析函数的形式使用 max()，例如

-- remove the comments -> see the output of max(...) over (...)
select 
  projectno,case
    when startdate = completiondate then 'on time'
    else 'delayed'
  end output_1,case 
    when 
      max( startdate ) over ( partition by projectno  )
    = max( completiondate )  over ( partition by projectno )
    then 'on time'
    else 'delayed'
  end output_2
--,max( startdate ) over ( partition by projectno  ) maxstart_
--,max( completiondate )  over ( partition by projectno ) maxcompletion_
from projects;

DBfiddle