Set the MissingSchemaAction property to the following prior to calling the Fill method, to autofill the column information from the backend data. It will automatically store the MaxLength of the columns:

MyDataAdapter.MissingSchemaAction = MissingSchemaAction.AddWithKey

>What i don't get is that in the Server explorer you can the size of a teble field, why you can't get it at run time with some property.