C#

 The below commnand ran successfully when i click the respective button but no changes on the database

SqlCommand command = new SqlCommand("select distinct * into #tmp From bounce delete from bounce insert into bounce select * from #tmp drop table #tmp)", connection);
connection.Close();
MessageBox.Show("Cleared Duplicates");
 
 
Note: Table bounce having only one column called email to remove the duplicates I created this button function

public static bool ContainsReservedXmlCharacters(string value)
{
 // This array can be stored in a static class so it's only created once
 char[] reservedCharacters = new char[] { '<', '>', '&', '%' };  

 for (int i = 0; i < value.Length; ++i)
 {
  if (Array.Exists(reservedCharacters, delegate (char c) { return c.Equals(value[i]); }))
    return true;
 }

 return false;
}

public static void ValidateForXml(ref string value)
{
 if (ContainsReservedXmlCharacters(value))
 {
  value = String.Format("<![CDATA[{0}]]>", value);
 }
}