/// <summary>
/// 过滤字符
/// </summary>
public static string Filter(string sInput)
{
    if (sInput == null || sInput.Trim() == string.Empty)
        return null;
    string sInput1 = sInput.ToLower();
    string output = sInput;
    string pattern = @",|.|?|!";
    if (Regex.Match(sInput1, Regex.Escape(pattern), RegexOptions.Compiled | RegexOptions.IgnoreCase).Success)
    {
        throw new Exception("字符串中含有非法字符!");
    }
    else
    {
        output = output.Replace("'", "''");
    }
    return output;
}