问如何在C#中处理特定的SQL异常(例如，违反唯一约束)？

EN

Try
    ...
Catch ex as SqlException When ex.Number = ...
    ...
Catch ex as SqlException When ex.Number = ...
    ...
End Try

try
{
    ...
}
catch (SqlException ex) when (ex.Number == ...)
{
    ...
}
catch (SqlException ex) when (ex.Number == ...)
{
    ...
}

try {
}
catch (SqlException ex)
{
 string str;
        str = "Source:"+ ex.Source;        
        str += "\n"+ "Number:"+ ex.Number.ToString();
        str += "\n"+ "Message:"+ ex.Message;
        str += "\n"+ "Class:"+ ex.Class.ToString ();
        str += "\n"+ "Procedure:"+ ex.Procedure.ToString();
        str += "\n"+ "Line Number:"+ex.LineNumber.ToString();
        str += "\n"+ "Server:"+ ex.Server.ToString();

        Console.WriteLine (str, "Database Exception");
}