Question

我参与了需要按日期构建直方图的项目。在我之前，在Java代码中完成了大量的SQL查询到每个矩形（日期子区域）的数据库。

我尝试了另一种方法：

select sum(CNT), trunc(DATE, 'MM') from DATA
  where DATE >= TO_DATE('01-01-2012','DD-MM-YYYY')
  and INC_DATE <= TO_DATE('31-12-2012','DD-MM-YYYY')
  group by trunc(DATE, 'MM')
  order by trunc(DATE, 'MM');

并从Java代码中收集ResultSet中的数据。但如果某个月没有数据，我会在直方图中错过矩形！

是否有可能修复SQL（或可能是PL / SQL）表达式以包含零和的结果中缺少日期？

或者如何在Java中构建更优雅的日期序列生成器以查找缺少的日期（与天/月/季/年对齐）？

Answer 1

尝试类似这样的事情（简化示例）：

with 
months_int as
(select trunc(min(inc_date), 'MM') min_month, trunc(max(inc_date), 'MM') max_month
 from data),
months as
(
  select add_months(min_month, level-1) mnth_date
  from months_int 
  connect by add_months(min_month, level-1)<= max_month
  )
select  mnth_date, sum(cnt) 
from data  right outer join months on trunc(inc_date, 'MM') = mnth_date
group by mnth_date
order by mnth_date

Here is a sqlfiddle example

Answer 2

您需要先创建日期列表;通过创建calender table或使用CONNECT BY语法。

select to_date('01-01-2012','DD-MM-YYYY') + level - 1
  from dual
connect by level <= to_date('31-12-2012','DD-MM-YYYY') 
                    - to_date('01-01-2012','DD-MM-YYYY') + 1

然后，您可以将此外部联接到您的主查询，以确保填充空白：

with the_dates as (
  select to_date('01-01-2012','DD-MM-YYYY') + level - 1 as the_date
    from dual
 connect by level <= to_date('01-01-2012','DD-MM-YYYY') 
                      - to_date('31-12-2012','DD-MM-YYYY') + 1
         )
select sum(b.cnt), trunc(a.the_date, 'MM') 
  from the_dates a
  left outer join data b
    on a.the_date = b.date
 group by trunc(a.the_date, 'MM')
 order by trunc(a.the_date, 'MM')

您不再需要WHERE子句，因为这在JOIN中得到了解决。请注意，我没有使用主表中的DATE列，而是使用生成的日期列。如果您希望将日期修改为不是月末，但是如果您希望按月进行修改，则可以在WITH子句中截断日期。在执行此操作之前，您应该知道索引。如果你的表在DATE而不是TRUNC(DATE, 'MM')被编入索引，那么最好只在DATE加入。

DATE是列的错误名称，因为它是保留字;我怀疑你没有使用它，但你应该知道。

如果您使用日历表，它看起来像这样：

select sum(b.cnt), trunc(a.the_date, 'MM') 
  from calender_table a
  left outer join data b
    on a.the_date = b.date
 where a.the_date >= to_date('01-01-2012','DD-MM-YYYY') 
   and a.the_date <= to_date('31-12-2012','DD-MM-YYYY')
 group by trunc(a.the_date, 'MM')
 order by trunc(a.the_date, 'MM')

Answer 3

我的生产代码基于当地大师的建议和@Ben技术：


-- generate sequence 1..N:
SELECT level FROM dual CONNECT BY level <= 4;

-- generates days:
select to_date('01-01-2012','DD-MM-YYYY') + level - 1
  from dual
connect by level <= to_date('31-12-2012','DD-MM-YYYY') - to_date('01-01-2012','DD-MM-YYYY') + 1;

with dates as (
  select (to_date('01-01-2012','DD-MM-YYYY') + level - 1) as daterange
    from dual
    connect by level <= to_date('31-12-2012','DD-MM-YYYY') - to_date('01-01-2012','DD-MM-YYYY') + 1
  ) select sum(tbl.cnt) as summ, trunc(dates.daterange, 'DDD')
      from dates
           left outer join DATA_TBL tbl
        on trunc(tbl.inc_date, 'DDD') = trunc(dates.daterange, 'DDD')
      group by trunc(dates.daterange, 'DDD')
      order by trunc(dates.daterange, 'DDD');

-- generates months:
select ADD_MONTHS(to_date('01-01-2012','DD-MM-YYYY'), level - 1)
  from dual
connect by level <= months_between(to_date('31-12-2012','DD-MM-YYYY'), to_date('01-01-2012','DD-MM-YYYY')) + 1;

with dates as (
  select add_months(to_date('01-01-2012','DD-MM-YYYY'), level-1) as daterange
    from dual
    connect by level <= months_between(to_date('31-12-2012','DD-MM-YYYY'), to_date('01-01-2012','DD-MM-YYYY')) + 1
  ) select sum(tbl.cnt) as summ, trunc(dates.daterange, 'MM')
      from dates
           left outer join DATA_TBL tbl
        on trunc(tbl.inc_date, 'MM') = trunc(dates.daterange, 'MM')
      group by trunc(dates.daterange, 'MM')
      order by trunc(dates.daterange, 'MM');

-- generates quarters:
select ADD_MONTHS(to_date('01-01-2012','DD-MM-YYYY'), (level-1)*3)
  from dual
  connect by level <= months_between(to_date('31-12-2012','DD-MM-YYYY'), to_date('01-01-2012','DD-MM-YYYY'))/3 + 1;

with dates as (
  select add_months(to_date('01-01-2012','DD-MM-YYYY'), (level-1)*3) as daterange
    from dual
    connect by level <= months_between(to_date('31-12-2012','DD-MM-YYYY'), to_date('01-01-2012','DD-MM-YYYY'))/3 + 1
  ) select sum(tbl.cnt) as summ, trunc(dates.daterange, 'Q')
      from dates
           left outer join DATA_TBL tbl
        on trunc(tbl.inc_date, 'Q') = trunc(dates.daterange, 'Q')
      group by trunc(dates.daterange, 'Q')
      order by trunc(dates.daterange, 'Q');

-- generates years:
select add_months(to_date('01-01-2007','DD-MM-YYYY'), (level-1)*12)
  from dual
  connect by level <= months_between(to_date('31-01-2012','DD-MM-YYYY'), to_date('01-01-2007','DD-MM-YYYY'))/12 + 1;

with dates as (
  select add_months(to_date('01-01-2007','DD-MM-YYYY'), (level-1)*12) as daterange
    from dual
    connect by level <= months_between(to_date('31-01-2012','DD-MM-YYYY'), to_date('01-01-2007','DD-MM-YYYY'))/12 + 1
  ) select sum(tbl.cnt) as summ, trunc(dates.daterange, 'YYYY')
      from dates
           left outer join DATA_TBL tbl
        on trunc(tbl.inc_date, 'YYYY') = trunc(dates.daterange, 'YYYY')
      group by trunc(dates.daterange, 'YYYY')
      order by trunc(dates.daterange, 'YYYY');

但按级别连接是根据以下内容进行攻击：

http://www.sqlsnippets.com/en/topic-11821.html（陷阱。使用PRIOR或不使用PRIOR，这是问题）

SQL截断/组/按日期排序（日/月/季/年），总和跳过日期，没有数据

3 个答案: