使用像while循环一样的递归公用表表达式

Question

我有下表

   Log

 Date            date
 Description     varchar
 ID              integer

给定日期作为参数,我必须找到否.或者每天从开始日期到使用递归cte后的一个月记录的日志数. 有些天可能没有任何日志,所以我必须将计数打印为0.

例如:

  select * from Log

回报

  1   insert      2011-01-17
  2   blah blah   2011-01-23
  3   blah        2011-07-07

对于2011-01-17作为输入,输出应该是

   2011-01-17    1
   2011-01-18    0
   2011-01-19    0
   ....
   2011-01-23    1
   .....
   2011-02-17    0

我必须使用递归 cte来做那个.我不知道如何在每次递归中将日期递增1以及如何停止\终止递归.

这是我到目前为止所做的事情:

 with cte as    (
    select '2011-01-17' as dat,count(*) as count 
from log group by date 
having date='2011-01-17' 

union all 

select dateadd(day,1,dat) as dat,count(*) as count 
from log,cte 
group by date 
having date=dateadd(day,1,dat) 
where dat<'2011-02-17' 
) 
select * from cte

Answer 1

WITH    days (d, maxd) AS
        (
        SELECT  MIN(date), MAX(date)
        FROM    log
        UNION ALL
        SELECT  DATEADD(day, 1, d), maxd
        FROM    days
        WHERE   d < maxd
        )
SELECT  d, COUNT(id)
FROM    days
LEFT JOIN
        log l
ON      l.date = d
GROUP BY
        d