DataSet ds = new DataSet(); 
String strXML;
SqlConnection con = new SqlConnection ("User ID=sa; Password=pwd; Initial Catalog=Pubs; Data Source=servername); 

SqlDataAdapter da = new SqlDataAdapter("SELECT emp_id, fname, lname, hire_date FROM Employee WHERE minit='M'", con); 
da.Fill(ds);

strXML = ds.GetXml(); 

System.Xml.XmlDocument objDoc = new System.Xml.XmlDocument();
System.Xml.XmlNodeList objNodeLst;

objDoc.LoadXml(strXML);
// LoadXml method is used to load the XML from the string into the XmlDocument.

objNodeLst = objDoc.SelectNodes("//NewDataSet/Table/hire_date");
foreach(System.Xml.XmlNode objNode in objNodeLst)
{
        //DateTime value is formatted here as per your need.
	DateTime dt = DateTime.Parse(objNode.InnerText);  
	objNode.InnerText = dt.ToShortDateString(); 

}
strXML=objDoc.InnerXml;