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Checking DateTime

Author

Topic

jafrywilson
Constraint Violating Yak Guru

379 Posts

Posted - 2012-05-22 : 03:37:55

my table is like this

id start_date end_date
1 2012-05-01 08:30:00.000 2012-05-30 09:30:00.000

if i am adding another row like

start_date 2012-05-01 09:00:00.000

it should not be inserted ..

how to check this condition ?

thanks for your reply

khtan
In (Som, Ni, Yak)

17689 Posts

Posted - 2012-05-22 : 05:28:52

quote:
it could not be inserted ..

What is the error message ?

KH
[spoiler]Time is always against us[/spoiler]

madhivanan
Premature Yak Congratulator

22864 Posts

Posted - 2012-05-22 : 06:46:10

So the same start_date should not be added again?

Madhivanan

Failing to plan is Planning to fail

jafrywilson
Constraint Violating Yak Guru

379 Posts

Posted - 2012-05-22 : 08:46:20

Yes.. Start_date should not be added again if the start date is same even in between the start and end_time...

It is an appointment table.. When im having one appointment I should not insert another appointment

jafrywilson
Constraint Violating Yak Guru

379 Posts

Posted - 2012-05-22 : 08:47:16

quote:
Originally posted by khtan

quote:
it could not be inserted ..

What is the error message ?

KH
[spoiler]Time is always against us[/spoiler]

sorry for my poor english

Lamprey
Master Smack Fu Yak Hacker

4614 Posts

Posted - 2012-05-22 : 10:53:04

I know you can apply that logic with a trigger. You might also be able to use a check constraint with a function.

jafrywilson
Constraint Violating Yak Guru

379 Posts

Posted - 2012-05-26 : 07:50:16

Thanks for your reply..

How to write query to check this condition...

visakh16
Very Important crosS Applying yaK Herder

52326 Posts

Posted - 2012-05-26 : 22:10:33

quote:
Originally posted by jafrywilson

Thanks for your reply..

How to write query to check this condition...

you need to use check constraint with a udf like below

http://visakhm.blogspot.com/2012/05/implementing-multiple-table-based-check.html

in your case function will be


CREATE FUNCTION CheckDateOverlap
(
@Date datetime
)
RETURNS bit 
AS
BEGIN
DECLARE @Ret bit

SELECT @Ret = CASE WHEN COALESCE(Cnt,0) > 0 THEN 0 ELSE 1 END
FROM (SELECT COUNT(*) AS Cnt
      FROM tablename
      WHERE start_date < @date
      AND end_date > @Date
     )t

RETURN (@ret)
END


then use it in check constraint like

ALTER TABLE  tablename ADD CONSTRAINT Chk_DateOverlap CHECK (dbo.CheckDateOverlap(start_date) = 1 )

------------------------------------------------------------------------------------------------------
SQL Server MVP
http://visakhm.blogspot.com/

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