I'm using DDT to setup a new database.  When I started I uncheked "Allow Null default value."  Don't know why - just thought that's what I was supposed to do...

I was able to setup my table and put fields on a form - no problems. 

I decided to add a couple of fields and the deployment to the server fails - b/c "Allow Null" is not checked (like the other fields.)  If I check the field - the deployment works - but the app fails with a "Conversion from type 'DBNull' to type 'String' is not valid."

Just need someone to tell me where I messed up and how to fix it - thanks!

HB

So...let me be sure I've got this straight...

When I setup the table - I am correct in unchecking the "Allow Nulls" checkbox - and when adding fields, I need to be sure there is a default value and the "Allow Nulls" is not checked.  Is that right?

Correct.  You really don't want to allow null values within a database if you have control over it.  When you initially create your structures, you can leave the Default blank and not select Allow Nulls and deploy without any type of error as you are deploying a new structure where there are no records...thus no field values have to be initialized.  But when you go back into that structure and add new columns to an already deployed table, you will want to be sure to supply a default value, otherwise you will run into the issue that you experienced.  But it is best to not allow nulls.

Thanks for the help...again...

No problem