Question

private const String FormatOverrideCols = 
  "<XmlDS><table1><col1>Value1</col1></table1><table1><col1>Value2</col1></table1></XmlDS>";

System.IO.StringReader xmlSR = new System.IO.StringReader(FormatOverrideCols);
ds.ReadXml(xmlSR, XmlReadMode.IgnoreSchema);

Why does this code snippet not load the data in the xml string into the dataset ??

Answer 1

Note the documentation on XmlReadMode.IgnoreSchema

Ignores any inline schema and loads
the data into the existing DataSet
schema. Any data that does not match
the existing schema is discarded. If
no schema exists in the DataSet, no
data is loaded.

If you are going to ignore the schema, you need to match the existing dataset schema. Alter (or omit) your read mode if your goal is to use the schema from the XML directly.

using (StringReader xmlSR = new StringReader(FormatOverrideCols))
{       
     ds.ReadXml(xmlSR); 
}