The dataset is created with a DOUBLE datatype instead of a DECIMAL datatype for the numeric column.

da.FillSchema(ds,SchemaType.Source);
            ds.WriteXmlSchema(AppDomain.CurrentDomain.BaseDirectory + @"\ds_1.txt");

Returns this...

<?xml version="1.0" standalone="yes"?>
<xs:schema id="NewDataSet" xmlns="" xmlns:xs="http://www.w3.org/2001/XMLSchema" xmlns:msdata="urn:schemas-microsoft-com:xml-msdata">
  <xs:element name="NewDataSet" msdata:IsDataSet="true" msdata:UseCurrentLocale="true">
    <xs:complexType>
      <xs:choice minOccurs="0" maxOccurs="unbounded">
        <xs:element name="Table">
          <xs:complexType>
            <xs:sequence>
              <xs:element name="A" type="xs:double" minOccurs="0" />
            </xs:sequence>
          </xs:complexType>
        </xs:element>
      </xs:choice>
    </xs:complexType>
  </xs:element>
</xs:schema>

I understand I need to change it from xs:double to Decimal type before filling the dataset in order to get accurate data.

Can someone tell me how to do that?