Apparently when using the DataSet.ReadXMLSchema, if you want a string field to have a DefaultValue of "" this is not interpreted correctly when the table is built. The DefaultValue for the field ends up being DBNull.

Here's a sample segment (which was written originally by DataSet.WriteXMLSchema):
Code:
<xs:element name="Bonus" msdata:CaseSensitive="True">
	<xs:complexType>
		<xs:sequence>
			<xs:element name="Name" type="xs:string" />
			<xs:element name="Value" type="xs:string" default="" minOccurs="0" />
		</xs:sequence>
	</xs:complexType>
</xs:element>
Irritating as I will have to go change a bunch of code to cope with this! Heads up!