我需要将默认数据替换为不存在的一行。下面是我所拥有的数据,然后是我需要返回的数据。我希望在SQL中执行此操作,而不是在PL / SQL中构建内容。我正在使用Oracle 8i。
我有什么:
Item Period_start_date Qty_Used
1234 1-MAR-2015 10
1234 1-JUN-2015 32
1234 1-JUL-2015 14
1234 1-SEP-2015 11
我需要什么:
1234 1-MAR-2015 10
1234 1-APR-2015 0
1234 1-MAY-2015 0
1234 1-JUN-2015 32
1234 1-JUL-2015 14
1234 1-AUG-2015 0
1234 1-SEP-2015 11
答案 0 :(得分:3)
使用8i使其比以后的版本更复杂。
您可以使用分层查询生成现有数据所涵盖范围内所有月份的列表,从最早的日期和月数开始:
select item, min(period_start_date) min_date,
months_between(max(period_start_date), min(period_start_date)) as num_months
from your_table
group by item
...并将其用作分层查询的内部查询:
select item, add_months(min_date, level) as period_start_date
from (
select item, min(period_start_date) min_date,
months_between(max(period_start_date), min(period_start_date)) as num_months
from your_table
group by item
)
connect by level < num_months
在这种情况下,对于4月到8月,这给了你六个虚拟行。 (我们知道三月或九月我们不需要虚拟行。)
然后,您可以使用not exists
排除任何具有相同日期的实际数据的内容;并与真实表中的数据联合起来:
select item, period_start_date, qty_used
from your_table
union all
select item, period_start_date, 0
from (
select item, add_months(min_date, level) as period_start_date
from (
select item, min(period_start_date) min_date,
months_between(max(period_start_date), min(period_start_date)) as num_months
from your_table
group by item
)
connect by level < num_months
) t
where not exists (
select null
from your_table
where item = t.item
and period_start_date = t.period_start_date
)
order by item, period_start_date;
ITEM PERIOD_STAR QTY_USED
---------- ----------- ----------
1234 01-MAR-2015 10
1234 01-APR-2015 0
1234 01-MAY-2015 0
1234 01-JUN-2015 32
1234 01-JUL-2015 14
1234 01-AUG-2015 0
1234 01-SEP-2015 11
使用固定的开始日期,您可以修改生成的表格:
select item, period_start_date, qty_used
from your_table
union all
select item, period_start_date, 0
from (
select item, add_months(date '2013-03-01', level - 1) as period_start_date
from (select distinct item from your_table)
connect by add_months(date '2013-03-01', level - 1) < sysdate
) t
where not exists (
select null
from your_table
where item = t.item
and period_start_date = t.period_start_date
)
order by item, period_start_date;
您也可以从生成的表数据中保留外连接,但当然必须使用旧的Oracle特定语法:
select t.item, t.period_start_date, nvl(yt.qty_used, 0) as qty
from (
select item, add_months(date '2013-03-01', level - 1) as period_start_date
from (select distinct item from your_table)
connect by add_months(date '2013-03-01', level - 1) < sysdate
) t, your_table yt
where yt.item (+) = t.item
and yt.period_start_date (+) = t.period_start_date
order by t.item, t.period_start_date;