use recursive common table expressions like a while loop

Question

i have the following table

   Log

 Date            date
 Description     varchar
 ID              integer

Given a date as a parameter,i have to find the no. or count of logs logged each day from start date to a month after it using recursive cte. Some Days may have not any logs,so i have to print the count as 0.

ex:

  select * from Log

returns

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

For 2011-01-17 as input,the output should be

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

I have to use recursive cte to do that.i don't know how to increment the date by 1 in each recursion and how to stop\terminate the recursion.

This is the thing i have done so far:

 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

Many basic samples will show you how to do that. At least provide what you have tried so far. — leppie, Jul 14 '11 at 11:13

score 5 · Accepted Answer · answered Jul 14 '11 at 11:14

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

use recursive common table expressions like a while loop

1 Answers1