CHECKSUM , Produces Same Hash For Two Different Inputs. Is This Right?

Hi,

We are using binary_checksum in some of instead of update trigger. The problem came into the knowledge when update falied without raising any error. We came to know after research that checksum returns same number for two different inputs and thats why update failed.

We are using following type of inside the trigger.



UPDATE [dbo].[Hospital]

SET

[HospitalID]= I.[HospitalID],

[Name]= I.[Name],

[HospitalNumber]= I.[HospitalNumber],

[ServerName] = I.[ServerName],

[IsAuthorized]= I.[IsAuthorized],

[IsAlertEnabled]= I.[IsAlertEnabled],

[AlertStartDate]= I.[AlertStartDate],

[AlertEndDate]= I.[AlertEndDate],

[IsTraining]= I.[IsTraining],

[TestMessageInterval]= I.[TestMessageInterval],

[DelayAlertTime]= I.[DelayAlertTime],

[IsDelayMessageAlert]= I.[IsDelayMessageAlert],

[IsTestMessageAlert]= I.[IsTestMessageAlert],

[IsUnAuthorizedMessageAlert]= I.[IsUnAuthorizedMessageAlert],

[IsWANDownAlert]= I.[IsWANDownAlert],

[IsWANUpAlert]= I.[IsWANUpAlert],

[CreateUserID]= Hospital.[CreateUserID],

[CreateWorkstationID]= Hospital.[CreateWorkstationID],

[CreateDate]= Hospital.[CreateDate] ,

/* record created date is never updated */

[ChangeUserID]= suser_name(),

[ChangeWorkstationID]= host_name(),

[ChangeDate]= getdate() ,

/* Updating the record modified field to now */

[CTSServerID]= I.[CTSServerID]

FROM inserted i

WHERE

i.[HospitalID]= Hospital.[HospitalID]

AND binary_checksum(

Hospital.[HospitalID],

Hospital.[Name],

Hospital.[HospitalNumber],

Hospital.[ServerName],

Hospital.[IsAuthorized],

Hospital.[IsAlertEnabled],

Hospital.[AlertStartDate],

Hospital.[AlertEndDate],

Hospital.[IsTraining],

Hospital.[TestMessageInterval],

Hospital.[DelayAlertTime],

Hospital.[IsDelayMessageAlert],

Hospital.[IsTestMessageAlert],

Hospital.[IsUnAuthorizedMessageAlert],

Hospital.[IsWANDownAlert],

Hospital.[IsWANUpAlert]) !=

binary_checksum(

I.[HospitalID],

I.[Name],

I.[HospitalNumber],

I.[ServerName],

I.[IsAuthorized],

I.[IsAlertEnabled],

I.[AlertStartDate],

I.[AlertEndDate],

I.[IsTraining],

I.[TestMessageInterval],

I.[DelayAlertTime],

I.[IsDelayMessageAlert],

I.[IsTestMessageAlert],

I.[IsUnAuthorizedMessageAlert],

I.[IsWANDownAlert],

I.[IsWANUpAlert]) ;





Here is the checksum example which produces same results for two different input.





DECLARE @V1 VARCHAR(10)

DECLARE @V2 VARCHAR(10)

SELECT @V1 = NULL, @V2=NULL

SELECT binary_checksum('KKK','San Jose','1418','1418SVR ',0,1,@V1,@V2,0,30,180,1,0,1,1,1),

binary_checksum('KKK','San Jose','1418','1418SVR ',1,1,@V1,@V2,0,30,180,1,1,1,1,1)



Lookat the two binary_checksum above, they are different and should not match, but they both return same value.



Can someone please provide some info on these.