I'm trying to retrieve the latest set of rows from a source table containing a foreign key, a date and other fields present. A sample set of data could be:
create table #tmp (primaryId int, foreignKeyId int, startDate datetime,
otherfield varchar(50))
insert into #tmp values (1, 1, '1 jan 2010', 'test 1')
insert into #tmp values (2, 1, '1 jan 2011', 'test 2')
insert into #tmp values (3, 2, '1 jan 2013', 'test 3')
insert into #tmp values (4, 2, '1 jan 2012', 'test 4')
The form of data that I'm hoping to retrieve is:
foreignKeyId maxStartDate otherfield
------------ ----------------------- -------------------------------------------
1 2011-01-01 00:00:00.000 test 2
2 2013-01-01 00:00:00.000 test 3
That is, just one row per foreignKeyId showing the latest start date and associated other fields - the primaryId is irrelevant.
I've managed to come up with:
select t.foreignKeyId, t.startDate, t.otherField from #tmp t
inner join (
select foreignKeyId, max(startDate) as maxStartDate
from #tmp
group by foreignKeyId
) s
on t.foreignKeyId = s.foreignKeyId and s.maxStartDate = t.startDate
but (a) this uses inner queries, which I suspect may lead to performance issues, and (b) it gives repeated rows if two rows in the original table have the same foreignKeyId and startDate.
Is there a query that will return just the first match for each foreign key and start date?
Depending on your sql server version, try the following:
select *
from (
select *, rnum = ROW_NUMBER() over (
partition by #tmp.foreignKeyId
order by #tmp.startDate desc)
from #tmp
) t
where t.rnum = 1
If you wanted to fix your attempt as opposed to re-engineering it then
select t.foreignKeyId, t.startDate, t.otherField from #tmp t
inner join (
select foreignKeyId, max(startDate) as maxStartDate, max(PrimaryId) as Latest
from #tmp
group by foreignKeyId
) s
on t.primaryId = s.latest
would have done the job, assuming PrimaryID increases over time.
Qualms about inner query would have been laid to rest as well assuming some indexes.
Using SQL Server 2005.
Data is in 2 separate tables and I have only been given write permissions.
Data looks like:
DateTime1 | DateTime2
-----------------------
2012-06-01 | 2012-06-01
2012-06-02 | 2012-06-02
2012-06-04 | 2012-06-05
2012-06-02 | NULL
NULL | 2012-06-05
2012-06-04 | 2012-06-05
NULL | NULL
What I am trying to do is be able to count values in which DateTime1 and DateTime2 contain values, DateTime1 contains a date and DateTime2 is NULL, DateTime1 is NULL and DateTime2 contains values.
Overall Im trying to avoid DateTime1 being Null and DateTime2 being null.
My where statement looks like this:
Where (DateTime1 is not null or DateTime2 is not null)
The only problem is it is still showing where both are null values. Anyone know why this might be happening or how to solve it?
Thanks
EDIT
Full Query as requested by #Lamak
;With [CTE] As (
Select
TH.ID
,AMT
,Reason
,EffDate
,DateReq
,CS_ID
,ROW_NUMBER()
Over (Partition By ID Order By [pthPrimeKey] Desc) as [RN]
From
DateTime1Table as [MC] (nolock)
Left Join History as [TH] (nolock) on [TH].[ID] = [MC].[ID]
Left Join Trans as [SUB] (nolock) on [SUB].TransactionReasonCode = [TH].Reason
Left Join Renew as [RM] (nolock) on [MC].ID = [RM].ID
Where
([MC].[DateTime1] is not null or [RM].[DateTime2] is not null)
And [PostingDate] = DATEADD(dd, datediff(dd, 1, GetDate()),0)
)
SELECT
[ID]
,[AMT] as [Earned]
,[Reason] as [Reason]
,[EffDate] as [Eff]
,[DateReq] as [Date_Cancel_Req]
,[pthUserId_Number] as [CSR]
FROM [CTE]
Where RN <= 1
The following will allow rows to be included if
only DateTime1 has a value
only DateTime2 has a value
both have values
It will exclude rows where both values are NULL. Is that what you're after? (I tried to follow the conversations but got lost, and wish you'd have a simpler repro with sample data - I think the CTE and all the other joins and logic really take away from the actual problem you're having.)
WHERE COALESCE([MC].[DateTime1], [RM].[DateTime2]) IS NOT NULL
However, since you're performing a LEFT OUTER JOIN, this may belong in the ON clause for [RM] instead of WHERE. Otherwise you won't know if a row is excluded because the value in a matching row was NULL, or because there was no matching row. And maybe that's ok, just thought I would mention it.
EDIT
Of course, that clause provides the exact same results as ...
WHERE ([MC].[DateTime1] is not null or [RM].[DateTime2] is not null)
Want proof?
DECLARE #a TABLE(id INT, DateTime1 DATETIME);
DECLARE #b TABLE(id INT, DateTime2 DATETIME);
INSERT #a SELECT 1, '20120602' ; INSERT #b SELECT 1, NULL;
INSERT #a SELECT 2, NULL ; INSERT #b SELECT 2, '20120605';
INSERT #a SELECT 3, '20120604' ; INSERT #b SELECT 3, '20120605';
INSERT #a SELECT 4, NULL ; INSERT #b SELECT 4, NULL;
INSERT #a SELECT 5, '20120602' ; INSERT #b SELECT 9, NULL;
INSERT #a SELECT 6, NULL ; INSERT #b SELECT 10, '20120605';
INSERT #a SELECT 7, '20120604' ; INSERT #b SELECT 11, '20120605';
INSERT #a SELECT 8, NULL ; INSERT #b SELECT 12, NULL;
SELECT * FROM #a AS a LEFT OUTER JOIN #b AS b
ON a.id = b.id
WHERE COALESCE(a.DateTime1, b.DateTime2) IS NOT NULL;
SELECT * FROM #a AS a LEFT OUTER JOIN #b AS b
ON a.id = b.id
WHERE a.DateTime1 IS NOT NULL OR b.DateTime2 IS NOT NULL;
Both queries yield:
id DateTime1 id DateTime2
-- ---------- ---- ----------
1 2012-06-02 1 NULL -- because left is not null
2 NULL 2 2012-06-05 -- because right is not null
3 2012-06-04 3 2012-06-05 -- because neither is null
5 2012-06-02 NULL NULL -- because of no match
7 2012-06-04 NULL NULL -- because of no match
So as I suggested in the comment, if you're not seeing the rows you expect, you need to look at other parts of the query. If you provide sample data and desired results, we can try to help you narrow that down. As it is, I don't think we know enough about your schema and data to determine where the problem is.
Suppose I have following table in Sql Server 2008:
ItemId StartDate EndDate
1 NULL 2011-01-15
2 2011-01-16 2011-01-25
3 2011-01-26 NULL
As you can see, this table has StartDate and EndDate columns. I want to validate data in these columns. Intervals cannot conflict with each other. So, the table above is valid, but the next table is invalid, becase first row has End Date greater than StartDate in the second row.
ItemId StartDate EndDate
1 NULL 2011-01-17
2 2011-01-16 2011-01-25
3 2011-01-26 NULL
NULL means infinity here.
Could you help me to write a script for data validation?
[The second task]
Thanks for the answers.
I have a complication. Let's assume, I have such table:
ItemId IntervalId StartDate EndDate
1 1 NULL 2011-01-15
2 1 2011-01-16 2011-01-25
3 1 2011-01-26 NULL
4 2 NULL 2011-01-17
5 2 2011-01-16 2011-01-25
6 2 2011-01-26 NULL
Here I want to validate intervals within a groups of IntervalId, but not within the whole table. So, Interval 1 will be valid, but Interval 2 will be invalid.
And also. Is it possible to add a constraint to the table in order to avoid such invalid records?
[Final Solution]
I created function to check if interval is conflicted:
CREATE FUNCTION [dbo].[fnIntervalConflict]
(
#intervalId INT,
#originalItemId INT,
#startDate DATETIME,
#endDate DATETIME
)
RETURNS BIT
AS
BEGIN
SET #startDate = ISNULL(#startDate,'1/1/1753 12:00:00 AM')
SET #endDate = ISNULL(#endDate,'12/31/9999 11:59:59 PM')
DECLARE #conflict BIT = 0
SELECT TOP 1 #conflict = 1
FROM Items
WHERE IntervalId = #intervalId
AND ItemId <> #originalItemId
AND (
(ISNULL(StartDate,'1/1/1753 12:00:00 AM') >= #startDate
AND ISNULL(StartDate,'1/1/1753 12:00:00 AM') <= #endDate)
OR (ISNULL(EndDate,'12/31/9999 11:59:59 PM') >= #startDate
AND ISNULL(EndDate,'12/31/9999 11:59:59 PM') <= #endDate)
)
RETURN #conflict
END
And then I added 2 constraints to my table:
ALTER TABLE dbo.Items ADD CONSTRAINT
CK_Items_Dates CHECK (StartDate IS NULL OR EndDate IS NULL OR StartDate <= EndDate)
GO
and
ALTER TABLE dbo.Items ADD CONSTRAINT
CK_Items_ValidInterval CHECK (([dbo].[fnIntervalConflict]([IntervalId], ItemId,[StartDate],[EndDate])=(0)))
GO
I know, the second constraint slows insert and update operations, but it is not very important for my application.
And also, now I can call function fnIntervalConflict from my application code before inserts and updates of data in the table.
Something like this should give you all overlaping periods
SELECT
*
FROM
mytable t1
JOIN mytable t2 ON t1.EndDate>t2.StartDate AND t1.StartDate < t2.StartDate
Edited for Adrians comment bellow
This will give you the rows that are incorrect.
Added ROW_NUMBER() as I didnt know if all entries where in order.
-- Testdata
declare #date datetime = '2011-01-17'
;with yourTable(itemID, startDate, endDate)
as
(
SELECT 1, NULL, #date
UNION ALL
SELECT 2, dateadd(day, -1, #date), DATEADD(day, 10, #date)
UNION ALL
SELECT 3, DATEADD(day, 60, #date), NULL
)
-- End testdata
,tmp
as
(
select *
,ROW_NUMBER() OVER(order by startDate) as rowno
from yourTable
)
select *
from tmp t1
left join tmp t2
on t1.rowno = t2.rowno - 1
where t1.endDate > t2.startDate
EDIT:
As for the updated question:
Just add a PARTITION BY clause to the ROW_NUMBER() query and alter the join.
-- Testdata
declare #date datetime = '2011-01-17'
;with yourTable(itemID, startDate, endDate, intervalID)
as
(
SELECT 1, NULL, #date, 1
UNION ALL
SELECT 2, dateadd(day, 1, #date), DATEADD(day, 10, #date),1
UNION ALL
SELECT 3, DATEADD(day, 60, #date), NULL, 1
UNION ALL
SELECT 4, NULL, #date, 2
UNION ALL
SELECT 5, dateadd(day, -1, #date), DATEADD(day, 10, #date),2
UNION ALL
SELECT 6, DATEADD(day, 60, #date), NULL, 2
)
-- End testdata
,tmp
as
(
select *
,ROW_NUMBER() OVER(partition by intervalID order by startDate) as rowno
from yourTable
)
select *
from tmp t1
left join tmp t2
on t1.rowno = t2.rowno - 1
and t1.intervalID = t2.intervalID
where t1.endDate > t2.startDate
declare #T table (ItemId int, IntervalID int, StartDate datetime, EndDate datetime)
insert into #T
select 1, 1, NULL, '2011-01-15' union all
select 2, 1, '2011-01-16', '2011-01-25' union all
select 3, 1, '2011-01-26', NULL union all
select 4, 2, NULL, '2011-01-17' union all
select 5, 2, '2011-01-16', '2011-01-25' union all
select 6, 2, '2011-01-26', NULL
select T1.*
from #T as T1
inner join #T as T2
on coalesce(T1.StartDate, '1753-01-01') < coalesce(T2.EndDate, '9999-12-31') and
coalesce(T1.EndDate, '9999-12-31') > coalesce(T2.StartDate, '1753-01-01') and
T1.IntervalID = T2.IntervalID and
T1.ItemId <> T2.ItemId
Result:
ItemId IntervalID StartDate EndDate
----------- ----------- ----------------------- -----------------------
5 2 2011-01-16 00:00:00.000 2011-01-25 00:00:00.000
4 2 NULL 2011-01-17 00:00:00.000
Not directly related to the OP, but since Adrian's expressed an interest. Here's a table than SQL Server maintains the integrity of, ensuring that only one valid value is present at any time. In this case, I'm dealing with a current/history table, but the example can be modified to work with future data also (although in that case, you can't have the indexed view, and you need to write the merge's directly, rather than maintaining through triggers).
In this particular case, I'm dealing with a link table that I want to track the history of. First, the tables that we're linking:
create table dbo.Clients (
ClientID int IDENTITY(1,1) not null,
Name varchar(50) not null,
/* Other columns */
constraint PK_Clients PRIMARY KEY (ClientID)
)
go
create table dbo.DataItems (
DataItemID int IDENTITY(1,1) not null,
Name varchar(50) not null,
/* Other columns */
constraint PK_DataItems PRIMARY KEY (DataItemID),
constraint UQ_DataItem_Names UNIQUE (Name)
)
go
Now, if we were building a normal table, we'd have the following (Don't run this one):
create table dbo.ClientAnswers (
ClientID int not null,
DataItemID int not null,
IntValue int not null,
Comment varchar(max) null,
constraint PK_ClientAnswers PRIMARY KEY (ClientID,DataItemID),
constraint FK_ClientAnswers_Clients FOREIGN KEY (ClientID) references dbo.Clients (ClientID),
constraint FK_ClientAnswers_DataItems FOREIGN KEY (DataItemID) references dbo.DataItems (DataItemID)
)
But, we want a table that can represent a complete history. In particular, we want to design the structure such that overlapping time periods can never appear in the database. We always know which record was valid at any particular time:
create table dbo.ClientAnswerHistories (
ClientID int not null,
DataItemID int not null,
IntValue int null,
Comment varchar(max) null,
/* Temporal columns */
Deleted bit not null,
ValidFrom datetime2 null,
ValidTo datetime2 null,
constraint UQ_ClientAnswerHistories_ValidFrom UNIQUE (ClientID,DataItemID,ValidFrom),
constraint UQ_ClientAnswerHistories_ValidTo UNIQUE (ClientID,DataItemID,ValidTo),
constraint CK_ClientAnswerHistories_NoTimeTravel CHECK (ValidFrom < ValidTo),
constraint FK_ClientAnswerHistories_Clients FOREIGN KEY (ClientID) references dbo.Clients (ClientID),
constraint FK_ClientAnswerHistories_DataItems FOREIGN KEY (DataItemID) references dbo.DataItems (DataItemID),
constraint FK_ClientAnswerHistories_Prev FOREIGN KEY (ClientID,DataItemID,ValidFrom)
references dbo.ClientAnswerHistories (ClientID,DataItemID,ValidTo),
constraint FK_ClientAnswerHistories_Next FOREIGN KEY (ClientID,DataItemID,ValidTo)
references dbo.ClientAnswerHistories (ClientID,DataItemID,ValidFrom),
constraint CK_ClientAnswerHistory_DeletionNull CHECK (
Deleted = 0 or
(
IntValue is null and
Comment is null
)),
constraint CK_ClientAnswerHistory_IntValueNotNull CHECK (Deleted=1 or IntValue is not null)
)
go
That's a lot of constraints. The only way to maintain this table is through merge statements (see examples below, and try to reason about why yourself). We're now going to build a view that mimics that ClientAnswers table defined above:
create view dbo.ClientAnswers
with schemabinding
as
select
ClientID,
DataItemID,
ISNULL(IntValue,0) as IntValue,
Comment
from
dbo.ClientAnswerHistories
where
Deleted = 0 and
ValidTo is null
go
create unique clustered index PK_ClientAnswers on dbo.ClientAnswers (ClientID,DataItemID)
go
And we have the PK constraint we originally wanted. We've also used ISNULL to reinstate the not null-ness of the IntValue column (even though the check constraints already guarantee this, SQL Server is unable to derive this information). If we're working with an ORM, we let it target ClientAnswers, and the history gets automatically built. Next, we can have a function that lets us look back in time:
create function dbo.ClientAnswers_At (
#At datetime2
)
returns table
with schemabinding
as
return (
select
ClientID,
DataItemID,
ISNULL(IntValue,0) as IntValue,
Comment
from
dbo.ClientAnswerHistories
where
Deleted = 0 and
(ValidFrom is null or ValidFrom <= #At) and
(ValidTo is null or ValidTo > #At)
)
go
And finally, we need the triggers on ClientAnswers that build this history. We need to use merge statements, since we need to simultaneously insert new rows, and update the previous "valid" row to end date it with a new ValidTo value.
create trigger T_ClientAnswers_I
on dbo.ClientAnswers
instead of insert
as
set nocount on
;with Dup as (
select i.ClientID,i.DataItemID,i.IntValue,i.Comment,CASE WHEN cah.ClientID is not null THEN 1 ELSE 0 END as PrevDeleted,t.Dupl
from
inserted i
left join
dbo.ClientAnswerHistories cah
on
i.ClientID = cah.ClientID and
i.DataItemID = cah.DataItemID and
cah.ValidTo is null and
cah.Deleted = 1
cross join
(select 0 union all select 1) t(Dupl)
)
merge into dbo.ClientAnswerHistories cah
using Dup on cah.ClientID = Dup.ClientID and cah.DataItemID = Dup.DataItemID and cah.ValidTo is null and Dup.Dupl = 0 and Dup.PrevDeleted = 1
when matched then update set ValidTo = SYSDATETIME()
when not matched and Dup.Dupl=1 then insert (ClientID,DataItemID,IntValue,Comment,Deleted,ValidFrom)
values (Dup.ClientID,Dup.DataItemID,Dup.IntValue,Dup.Comment,0,CASE WHEN Dup.PrevDeleted=1 THEN SYSDATETIME() END);
go
create trigger T_ClientAnswers_U
on dbo.ClientAnswers
instead of update
as
set nocount on
;with Dup as (
select i.ClientID,i.DataItemID,i.IntValue,i.Comment,t.Dupl
from
inserted i
cross join
(select 0 union all select 1) t(Dupl)
)
merge into dbo.ClientAnswerHistories cah
using Dup on cah.ClientID = Dup.ClientID and cah.DataItemID = Dup.DataItemID and cah.ValidTo is null and Dup.Dupl = 0
when matched then update set ValidTo = SYSDATETIME()
when not matched then insert (ClientID,DataItemID,IntValue,Comment,Deleted,ValidFrom)
values (Dup.ClientID,Dup.DataItemID,Dup.IntValue,Dup.Comment,0,SYSDATETIME());
go
create trigger T_ClientAnswers_D
on dbo.ClientAnswers
instead of delete
as
set nocount on
;with Dup as (
select d.ClientID,d.DataItemID,t.Dupl
from
deleted d
cross join
(select 0 union all select 1) t(Dupl)
)
merge into dbo.ClientAnswerHistories cah
using Dup on cah.ClientID = Dup.ClientID and cah.DataItemID = Dup.DataItemID and cah.ValidTo is null and Dup.Dupl = 0
when matched then update set ValidTo = SYSDATETIME()
when not matched then insert (ClientID,DataItemID,Deleted,ValidFrom)
values (Dup.ClientID,Dup.DataItemID,1,SYSDATETIME());
go
Obviously, I could have built a simpler table (not a join table), but this is my standard go-to example (albeit it took me a while to reconstruct it - I forgot the set nocount on statements for a while). But the strength here is that, the base table, ClientAnswerHistories is incapable of storing overlapping time ranges for the same ClientID and DataItemID values.
Things get more complex when you need to deal with temporal foreign keys.
Of course, if you don't want any real gaps, then you can remove the Deleted column (and associated checks), make the not null columns really not null, modify the insert trigger to do a plain insert, and make the delete trigger raise an error instead.
I've always taken a slightly different approach to the design if I have data that is never to have overlapping intervals... namely don't store intervals, but only start times. Then, have a view that helps with displaying the intervals.
CREATE TABLE intervalStarts
(
ItemId int,
IntervalId int,
StartDate datetime
)
CREATE VIEW intervals
AS
with cte as (
select ItemId, IntervalId, StartDate,
row_number() over(partition by IntervalId order by isnull(StartDate,'1753-01-01')) row
from intervalStarts
)
select c1.ItemId, c1.IntervalId, c1.StartDate,
dateadd(dd,-1,c2.StartDate) as 'EndDate'
from cte c1
left join cte c2 on c1.IntervalId=c2.IntervalId
and c1.row=c2.row-1
So, sample data might look like:
INSERT INTO intervalStarts
select 1, 1, null union
select 2, 1, '2011-01-16' union
select 3, 1, '2011-01-26' union
select 4, 2, null union
select 5, 2, '2011-01-26' union
select 6, 2, '2011-01-14'
and a simple SELECT * FROM intervals yields:
ItemId | IntervalId | StartDate | EndDate
1 | 1 | null | 2011-01-15
2 | 1 | 2011-01-16 | 2011-01-25
3 | 1 | 2011-01-26 | null
4 | 2 | null | 2011-01-13
6 | 2 | 2011-01-14 | 2011-01-25
5 | 2 | 2011-01-26 | null
Following is the sample data. I need to make 3 copies of this data in t sql without using loop and return as one resultset. This is sample data not real.
42 South Yorkshire
43 Lancashire
44 Norfolk
Edit: I need multiple copies and I have no idea in advance that how many copies I need I have to decide this on the basis of dates. Date might be 1st jan to 3rd Jan OR 1st jan to 8th Jan.
Thanks.
Don't know about better but this is definatley more creative! you can use a CROSS JOIN.
EDIT: put some code in to generate a date range, you can change the date range, the rows in the #date are your multiplier.
declare #startdate datetime
, #enddate datetime
create table #data1 ([id] int , [name] nvarchar(100))
create table #dates ([date] datetime)
INSERT #data1 SELECT 42, 'South Yorkshire'
INSERT #data1 SELECT 43, 'Lancashire'
INSERT #data1 SELECT 44, 'Norfolk'
set #startdate = '1Jan2010'
set #enddate = '3Jan2010'
WHILE (#startdate <= #enddate)
BEGIN
INSERT #dates SELECT #startdate
set #startdate=#startdate+1
END
SELECT [id] , [name] from #data1 cross join #dates
drop table #data1
drop table #dates
You could always use a CTE to do the dirty work
Replace the WHERE Counter < 4 with the amount of duplicates you need.
CREATE TABLE City (ID INTEGER PRIMARY KEY, Name VARCHAR(32))
INSERT INTO City VALUES (42, 'South Yorkshire')
INSERT INTO City VALUES (43, 'Lancashire')
INSERT INTO City VALUES (44, 'Norfolk')
/*
The CTE duplicates every row from CTE for the amount
specified by Counter
*/
;WITH CityCTE (ID, Name, Counter) AS
(
SELECT c.ID, c.Name, 0 AS Counter
FROM City c
UNION ALL
SELECT c.ID, c.Name, Counter + 1
FROM City c
INNER JOIN CityCTE cte ON cte.ID = c.ID
WHERE Counter < 4
)
SELECT ID, Name
FROM CityCTE
ORDER BY 1, 2
DROP TABLE City
This may not be the most efficient way of doing it, but it should work.
(select ....)
union all
(select ....)
union all
(select ....)
Assume the table is named CountyPopulation:
SELECT * FROM CountyPopulation
UNION ALL
SELECT * FROM CountyPopulation
UNION ALL
SELECT * FROM CountyPopulation
Share and enjoy.
There is no need to use a cursor. The set-based approach would be to use a Calendar table. So first we make our calendar table which need only be done once and be somewhat permanent:
Create Table dbo.Calendar ( Date datetime not null Primary Key Clustered )
GO
; With Numbers As
(
Select ROW_NUMBER() OVER( ORDER BY S1.object_id ) As [Counter]
From sys.columns As s1
Cross Join sys.columns As s2
)
Insert dbo.Calendar([Date])
Select DateAdd(d, [Counter], '19000101')
From Numbers
Where [Counter] <= 100000
GO
I populated it with a 100K dates which goes into 2300. Obviously you can always expand it. Next we generate our test data:
Create Table dbo.Data(Id int not null, [Name] nvarchar(20) not null)
GO
Insert dbo.Data(Id, [Name]) Values(42,'South Yorkshire')
Insert dbo.Data(Id, [Name]) Values(43, 'Lancashire')
Insert dbo.Data(Id, [Name]) Values(44, 'Norfolk')
GO
Now the problem becomes trivial:
Declare #Start datetime
Declare #End datetime
Set #Start = '2010-01-01'
Set #End = '2010-01-03'
Select Dates.[Date], Id, [Name]
From dbo.Data
Cross Join (
Select [Date]
From dbo.Calendar
Where [Date] >= #Start
And [Date] <= #End
) As Dates
By far the best solution is CROSS JOIN. Most natural.
See my answer here: How to retrieve rows multiple times in SQL Server?
If you have a Numbers table lying around, it's even easier. You can DATEDIFF the dates to give you the filter on the Numbers table