hello

I ran into a problem with NHibernate - "LastUpdate" field of my class defaults to null (NULL is declared in database table schema as well) but when inserted into NHibernate I got error:


I want to avoid hardcoding "NULL" to 1JAN1753 - any alternatives? Thanks

Do you use DateTime or DateTime? ? If you want to use NULL values you have to use DateTime? !

Yes I'm using DateTime in both my SQL table schema AND C# class definition (and mapping file NHibernate type)

[CreateDate] [datetime] NULL DEFAULT (GETDATE()),
[CreatedBy] [bigint] NULL DEFAULT (-1), /* TODO: Add constraint this will not be Constant.INVALID */
[LastUpdate] [datetime] NULL, << I can't insert NULL because of problem I mentioned
[LastUpdateBy] [bigint] NULL,

No, the problem ist that the allowed data range in .Net and in SQL Server differs. DateTime is a struct and therefore a value type. Meaning it can't be NULL. An uninitalized DateTime is something about "12:00:00 midnight, January 1, 0001 ". SQL Server has a minimum of "1/1/1753 12:00:00 AM and 12/31/9999 11:59:59 PM". If you really want NULL values you have to use the nullable version DateTime? in your class. Mapping with hibernate and schema definition in SQL Server stays the same.

http://msdn.microsoft.com/en-us/library/1t3y8s4s(VS.80).aspx

yes really want NULL in LastUpdate field in database - because support guys can use this syntax to find Person's who hasn't been updated.

SELECT * FROM Person WHERE LastUpdate is NULL

... instead of

SELECT * FROM Person WHERE LastUpdate>'1/1/1753'

Thanks