db2中复杂的sql查询需求
我的表格如下：db2中复杂的sql查询需求,sql,db2,Sql,Db2,我的表格如下： keyCol | date_O_Col | date_C_Col | statCol -------------------------------------------------------------------- 1 2007-02-09 2012-11-02 C 1 1990-01-31 <nu
keyCol | date_O_Col | date_C_Col | statCol
--------------------------------------------------------------------
1 2007-02-09 2012-11-02 C
1 1990-01-31 <null> O
1 <null> <null> O
------------------------------------------------------------------------
statCol keyCol | date_O_Col | date_C_Col | statCol
--------------------------------------------------------------------
2 2016-02-09 2016-03-09 C
2 1990-01-31 2012-11-02 C
2 2016-03-10 <null> O
------------------------------------------------------------------------
keyCol | date | O | Col | date | C | Col | statCol
--------------------------------------------------------------------
2 2016-02-09 2016-03-09 C
2 1990-01-31 2012-11-02 C
2 2016-03-10 O
------------------------------------------------------------------------
keyCol | date_O_Col | date_C_Col | statCol
--------------------------------------------------------------------
2 2016-03-10 <null> O
keyCol | date | O | Col | date | C | Col | statCol
--------------------------------------------------------------------
2 2016-03-10 O
2016-03-10date\u O\u ColstatCol我正在使用DB29。您可以使用
caseselect t.keycol,
(case when max(date_O_Col) is null and max(date_C_Col) is null then NULL
when max(date_O_Col) is null then 'C'
when max(date_C_Col) is null then 'O'
when max(date_O_Col) > max(date_C_Col) then 'O'
when max(date_C_Col) > max(date_O_Col) then 'C'
else '='
end)
from t
group by keycol;
我为您的问题没有涉及的边界情况编制了值：当值都为
NULLcaseselect t.keycol,
(case when max(date_O_Col) is null and max(date_C_Col) is null then NULL
when max(date_O_Col) is null then 'C'
when max(date_C_Col) is null then 'O'
when max(date_O_Col) > max(date_C_Col) then 'O'
when max(date_C_Col) > max(date_O_Col) then 'C'
else '='
end)
from t
group by keycol;
我为您的问题没有涉及的边界情况创建了值：当值都为
NULLSELECT keyCol,
CASE WHEN date_O_Col = x.date_col THEN date_O_Col END,
CASE WHEN date_C_Col = x.date_col THEN date_C_Col END,
statCol
FROM mytable
CROSS JOIN (
SELECT MAX(date_col) AS date_col
FROM (SELECT CASE
WHEN COALESCE([date_O_Col], '1900-01-01') >
COALESCE([date_C_Col], '1900-01-01')
THEN date_O_Col
ELSE date_C_Col
END AS date_col
FROM mytable) AS t) AS x
WHERE CASE
WHEN COALESCE([date_O_Col], '1900-01-01') >
COALESCE([date_C_Col], '1900-01-01')
THEN date_O_Col
ELSE date_C_Col
END = x.date_col
您可以使用以下查询：
SELECT keyCol,
CASE WHEN date_O_Col = x.date_col THEN date_O_Col END,
CASE WHEN date_C_Col = x.date_col THEN date_C_Col END,
statCol
FROM mytable
CROSS JOIN (
SELECT MAX(date_col) AS date_col
FROM (SELECT CASE
WHEN COALESCE([date_O_Col], '1900-01-01') >
COALESCE([date_C_Col], '1900-01-01')
THEN date_O_Col
ELSE date_C_Col
END AS date_col
FROM mytable) AS t) AS x
WHERE CASE
WHEN COALESCE([date_O_Col], '1900-01-01') >
COALESCE([date_C_Col], '1900-01-01')
THEN date_O_Col
ELSE date_C_Col
END = x.date_col
从我的答案到你的另一篇帖子 如果多行具有相同的最长日期，则不能描述所需的结果。简单假设一下，您需要所有的行，那么下面的操作就可以了
select *
from mytable
where (select max(max(coalesce(date1,'00001-01-01')
,coalesce(date2,'00001-01-01')
)
)
from mytable
) in (date1, date2)
从我的答案到你的另一个帖子 如果多行具有相同的最长日期，则不能描述所需的结果。简单假设一下，您需要所有的行，那么下面的操作就可以了
select *
from mytable
where (select max(max(coalesce(date1,'00001-01-01')
,coalesce(date2,'00001-01-01')
)
)
from mytable
) in (date1, date2)
我不确定我是否完全理解了这些要求，但在Charles提供的查询的引导下，下面的设置和查询可能是： 设置：
create table so39290083
( keyCol dec(1), date_O_Col date, date_C_Col date, statCol char)
;
insert into so39290083 values
/*keyCol dec(1), date_O_Col date, date_C_Col date, statCol char*/
( 1 , '2007-02-09' , '2012-11-02' , 'C' )
, ( 1 , '1990-01-31' , null , 'O' )
, ( 1 , NULL , null , 'O' )
, ( 2 , '2016-02-09' , '2016-03-09' , 'C' )
, ( 2 , '1990-01-31' , '2012-11-02' , 'C' )
, ( 2 , '2016-03-10' , null , 'O' )
;
select t.keycol
, case t.statcol when 'O' then date_O_Col end as date_O_Col
, case t.statcol when 'C' then date_C_Col end as date_C_Col
, t.statcol
from so39290083 as T
where ( t.keycol
, case t.statcol when 'O' then date_O_Col
when 'C' then date_C_Col end ) in
( select keycol
, max(max(coalesce( date_O_Col , date'0001-01-01')
,coalesce( date_C_Col , date'0001-01-01')
))
from so39290083 s
group by keycol
)
; -- likeness of a report from above query:
KEYCOL DATE_O_COL DATE_C_COL STATCOL
1 - 2012-11-02 C
2 2016-03-10 - O
******** End of data ********
我不确定我是否完全理解了这些要求，但在Charles提供的查询的引导下，下面的设置和查询可能是： 设置：
create table so39290083
( keyCol dec(1), date_O_Col date, date_C_Col date, statCol char)
;
insert into so39290083 values
/*keyCol dec(1), date_O_Col date, date_C_Col date, statCol char*/
( 1 , '2007-02-09' , '2012-11-02' , 'C' )
, ( 1 , '1990-01-31' , null , 'O' )
, ( 1 , NULL , null , 'O' )
, ( 2 , '2016-02-09' , '2016-03-09' , 'C' )
, ( 2 , '1990-01-31' , '2012-11-02' , 'C' )
, ( 2 , '2016-03-10' , null , 'O' )
;
select t.keycol
, case t.statcol when 'O' then date_O_Col end as date_O_Col
, case t.statcol when 'C' then date_C_Col end as date_C_Col
, t.statcol
from so39290083 as T
where ( t.keycol
, case t.statcol when 'O' then date_O_Col
when 'C' then date_C_Col end ) in
( select keycol
, max(max(coalesce( date_O_Col , date'0001-01-01')
,coalesce( date_C_Col , date'0001-01-01')
))
from so39290083 s
group by keycol
)
; -- likeness of a report from above query:
KEYCOL DATE_O_COL DATE_C_COL STATCOL
1 - 2012-11-02 C
2 2016-03-10 - O
******** End of data ********
你的答案似乎不完整。该查询应产生4列，如我的示例中所述。但上面的答案似乎只返回了两列。另外，如果可能的话，请你解释一下。你的回答似乎不完整。该查询应产生4列，如我的示例中所述。但上面的答案似乎只返回了两列。另外，如果可能的话，请您解释一下。它返回0结果：（@Vicky我已经用第二组样本数据对它进行了测试，它返回了正确的结果。请注意，
[date\u O\u Col][date\u O\u Col]年合并（日期1，日期'0001-01-01'）年合并（日期1，日期'0001-01-01'）