Hello,

I am trying to save an entity with a DateTime nullable field (allow nulls is true in the DB). When I turn on trace I see that the nullable field is not included in the UPDATE statement.

How can I save a null value in this case? I had been trying entityName.Field = null. No exceptions are thrown, it just is not included in the UPDATE to the DB.

Using adapter with MS SQL 2005 with LLBLGEN 2.5 Nov 5th build.

What was the value of this field before you set it to null?

Walaa wrote:

What was the value of this field before you set it to null?

The pre-existing value is valid DateTime (i.e. 2007-12-01 00:00:00).

The entity will save the correct DateTime if I save a DateTime value, it is only the null value that is being ignored.

As this information was missing, I assume you are using .NET 2.0, right? Was this field being generated as Nullable .NET Type? Otherwise you can use the folloiwng code:

myEntity.SetNewFieldValue((int)MyEntityFieldIndex.MyDateField, null);

Yes it is .Net 2.0 (2.5 technically).

1) Unfortunately your suggestion does not work. 2) When attempting using a nullabe date time, I try:

DateTime? nullDate = null; myEntity.MyField = nullDate;

And same problem.

Field is not included in UPDATE statement in both cases.

Yes it is .Net 2.0 (2.5 technically).

There is no .NET 2.5, either 1.0, 1.1, 2.0, 3.0 or 3.5 I think you have mistaken it with the LLBLGen Pro version.

1) Unfortunately your suggestion does not work.

Did you mean the following line didn't work?

myEntity.SetNewFieldValue((int)MyEntityFieldIndex.MyDateField, null);

2) When attempting using a nullabe date time, I try:

DateTime? nullDate = null; myEntity.MyField = nullDate;

And same problem.

So myEntity.MyField is of type "DateTime?", correct?

Oops, I mean't .Net v2.0.50727

Yes I tried:

myEntity.SetNewFieldValue((int)MyEntityFieldIndex.MyDateField, null);

Yes,

myEntity.MyField is type DateTime? (and allow nulls is set for this column in the DB)

strange.

Would you please attach a simple repro solution based on Northwind or on a schema of your own, but then you should also provide the appropriate script to create such schema?

I was hoping not to have to do that

Can you first attempt to save a null DateTime value into MS SQL 2005 to see if you can re-produce this?

Are there any designer options I am missing that could be causing this behavior? Again, any valid DateTime value will save properly.

And yes the designer sees this as a nullable column. The type in .Net is DateTime?

Did you fetch the entity before updating it? Would you at least post the corresponding code snippet, where you fetch/create the entity, modify the dateTime value and attemt to save it?

(EDIT) Might be the same issue as in here: http://www.llblgen.com/TinyForum/Messages.aspx?ThreadID=10817

Thats IT! Fetching the entity first will fix this problem.

Is there a way to set a single field to a null value without fetching first (making a DB trip) ?

Is there a way to set a single field to a null value without fetching first (making a DB trip) ?

Yes as shown in the previously linked thread, Set the IsChanged property to true:

youEntity.Fields["YourFieldName"].IsChanged = true;