string[] distinctcols = new string[(DTA.Columns.Count)];
foreach (DataColumn dc in DTA.Columns)
{
   distinctcols[dc.Ordinal] = dc.ColumnName;
}
DataView mydataview = new DataView(DTA);
DataTable DTB= mydataview.ToTable(true, distinctcols);

------解决方案--------------------

C# code

        public static bool CheckReduplicated(DataTable dt, ref string strMsg, params string[] keyFields)
        {
            string f = "";
            for (int i = 0; i < keyFields.Length; i++)
            {
                if (i != keyFields.Length - 1)
                    f += keyFields[i] + ",";
                else
                    f += keyFields[i] + " ASC";
            }

            dt.DefaultView.Sort = f;
            DataTable temp = dt.DefaultView.ToTable();
            for (int i = 0; i < temp.Rows.Count; i++)
            {
                DataRow dr = temp.Rows[i];
                if (i > 0)
                {
                    DataRow dr_pre = temp.Rows[i - 1];

                    bool isReduplicated = true;
                    foreach (string s in keyFields)
                    {
                        string value = dr[s].ToString();
                        string value_pre = dr_pre[s].ToString();

                        if (value != value_pre)
                        {
                            isReduplicated = false;
                        }
                    }

                    if (isReduplicated)
                    {
                        if (strMsg.Length > 0)
                        {
                            strMsg += "&nbsp;";
                        }

                        foreach (string s in keyFields)
                        {
                            strMsg += string.Format(@"[{0}:{1}]", s, dr[s].ToString());
                        }

                        strMsg += "有重复.";

                        return true;
                    }
                }
            }

            return false;
        }