if vlaue exists don't enter event c#
public bool rebateslip(int ticketID)
{
SqlCommand myCommand = new SqlCommand("SELECT ID FROM ticket WHERE ID = @ticketID", con);
SqlDataAdapter sqlDa = new SqlDataAdapter(myCommand);
myCommand.Parameters.AddWithValue("@ticketID", ticketID);
var reader = myCommand.Execute();
return reader.HasRows;
}