两列SQL计数查询，第一列具有静态标签

我正在使用Oracle 10g，我有一个名为downloads的表，基本上如下所示：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

等等

我希望执行一个返回以下内容的查询：

Downloads today
Downloads yesterday
Downloads from start date until today
Downloads on start date
Downloads on day after start date

我想将结果打印在两列中。在第一列中，我想放置一个静态标签，就像上面的标签一样。第二列是计数

我试过这样的方法：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

但这有两个问题。一，它只打印一列，计数。第二，如果给定日期（或日期范围）没有数据，则不打印任何内容。我需要打印一个零

然后我尝试了这样的方法：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

这将返回两列，但第一列不是静态的，它是数据库中的一个字段（下载日期）。更重要的是，它返回多行用于选择日期范围的查询（其中download_date>'2007-08-08'），而我只需要一行及其计数

我该怎么做

非常感谢,，

---

Bob

只需在union版本中的每个选项中添加一个静态标签，如下所示：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

---

首先。为此使用

Union All

。Union将删除双记录，这可能不是您在本例中想要的。这没什么大不了的，但工会的速度也更快

第二，我不明白为什么你不能只放一个静态标签，像这样：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

然后，您可以编写如下查询：

ID     DOWNLOAD_DATE
1      2011-02-10
2      2011-03-10
3      2011-04-10
4      2011-05-10
5      2011-01-11
6      2011-04-22
7      2011-02-18
8      2011-03-14
9      2011-02-01
10     2011-01-31

select count(id) from downloads where download_date = '2007-08-06'
union
select count(id) from downloads where download_date = '2007-08-08'

select download_date, count(download_date) from downloads where download_date = '2007-08-06'
group by download_date
union
select download_date, count(download_date) from downloads where download_date > '2007-08-08'
group by download_date

SELECT 'some label', ...
 UNION
 ...

select 'Look, static' from dual

select 
  'Downloads today' as Caption, 
  count(*) as DownloadCount 
from 
  Downloads where trunc(download_date) = trunc(sysdate)
union all
select 
  'Downloads yesterday'
  count(*)
from 
  Downloads where trunc(download_date) = trunc(sysdate) - 1

如果没有数据，计数将打印0