C#

string sql = "select LastName, FirstName, Company, <code>COALESCE(LastName, Company) AS ListData </code>"
             + "from TestTable";
SqlConnection conn = new SqlConnection(connString);
SqlDataAdapter da = new SqlDataAdapter(sql, conn);
DataSet dataset1 = new DataSet();
da.Fill(dataset1, "TestTable");
listBox1.DataSource = dataset1.Tables["TestTable"];
listBox1.DisplayMember = "<code>ListData</code>";

string sql = "select LastName, FirstName, Company "
             + "from TestTable";
SqlConnection conn = new SqlConnection(connString);
SqlDataAdapter da = new SqlDataAdapter(sql, conn);
DataSet dataset1 = new DataSet();
da.Fill(dataset1, "TestTable");
<code>dataset1.Tables["TestTable"].Columns.Add("ListData", 
                                         typeof(string), 
                                         "ISNULL(LastName,Company)");</code>
listBox1.DataSource = dataset1.Tables["TestTable"];
listBox1.DisplayMember = "ListData";

 Collapse Copy Code
try
{
    registertoken[line]=tobj.RegisterCallNotifications(ia[line],
                 true,true,TapiConstants.TAPIMEDIATYPE_AUDIO,2);    
    MessageBox.Show("Registration token : "+ 
                 registertoken[line], 
                 "Registration Succeed for line "+line);
}
catch(Exception ein)
{
    MessageBox.Show("Failed to register on line "+line,"Registration for calls");
}