Number of SQL days in a row
This is the SQL database data:
UserTable
UserName | UserDate | UserCode
-------------------------------------------
user1 | 08-31-2014 | 232
user1 | 09-01-2014 | 232
user1 | 09-02-2014 | 0
user1 | 09-03-2014 | 121
user1 | 09-08-2014 | 122
user1 | 09-09-2014 | 0
user1 | 09-10-2014 | 144
user1 | 09-11-2014 | 166
user2 | 09-01-2014 | 177
user2 | 09-04-2014 | 188
user2 | 09-05-2014 | 199
user2 | 09-06-2014 | 0
user2 | 09-07-2014 | 155
Only consecutive days should be considered (as a result) if [UserCode] is anything other than zero. UserDate is between 09-01-2014 and 09-11-2014. Show result only if the result is 2 or more.
I want my sql query to return:
UserName | StartDate | EndDate | Result
----------------------------------------------------------
user1 | 09-01-2014 | 09-03-2014 | 2
user1 | 09-08-2014 | 09-11-2014 | 3
user2 | 09-04-2014 | 09-07-2014 | 3
Can I only use a SQL query?
+3
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2 answers
This is the Gaps and Islands problem . The easiest way to solve this problem is to use ROW_NUMBER()
to identify gaps in the sequence:
SELECT UserName,
UserDate,
UserCode,
GroupingSet = DATEADD(DAY,
-ROW_NUMBER() OVER(PARTITION BY UserName
ORDER BY UserDate),
UserDate)
FROM UserTable;
This gives:
UserName | UserDate | UserCode | GroupingSet
------------+---------------+------------+-------------
user1 | 09-01-2014 | 1 | 08-31-2014
user1 | 09-02-2014 | 0 | 08-31-2014
user1 | 09-03-2014 | 1 | 08-31-2014
user1 | 09-08-2014 | 1 | 09-04-2014
user1 | 09-09-2014 | 0 | 09-04-2014
user1 | 09-10-2014 | 1 | 09-04-2014
user1 | 09-11-2014 | 1 | 09-04-2014
user2 | 09-01-2014 | 1 | 08-31-2014
user2 | 09-04-2014 | 1 | 09-02-2014
user2 | 09-05-2014 | 1 | 09-02-2014
user2 | 09-06-2014 | 0 | 09-02-2014
user2 | 09-07-2014 | 1 | 09-02-2014
As you can see, this gives a constant value in GroupingSet
for consecutive lines. Then you can group this code to get the summary you want:
WITH CTE AS
( SELECT UserName,
UserDate,
UserCode,
GroupingSet = DATEADD(DAY,
-ROW_NUMBER() OVER(PARTITION BY UserName
ORDER BY UserDate),
UserDate)
FROM UserTable
)
SELECT UserName,
StartDate = MIN(UserDate),
EndDate = MAX(UserDate),
Result = COUNT(NULLIF(UserCode, 0))
FROM CTE
GROUP BY UserName, GroupingSet
HAVING COUNT(NULLIF(UserCode, 0)) > 1
ORDER BY UserName, StartDate;
+11
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Try:
;with T1 as(
select
*,
ROW_NUMBER() over ( order by UserName, UserDate) ID
from tbl
)
,T as (
SELECT *, 1 CNT FROM T1 where ID=1
union all
SELECT b.*, (case when T.UserDate+1=b.UserDate and
T.UserName=b.UserName then t.CNT
else T.CNT+1 end)
from T1 b INNER JOIN T on b.ID=T.ID+1
)
select distinct UserName, MIN(UserDate), max(UserDate)
,sum(case UserCode when 0 then 0 else 1 end) From T group by UserName, CNT
having COUNT(*)>1
0
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