ADO.NET กับ Excel สอบถามการเขียนโปรแกรมติดต่อกับ Excel ในการดึงเอาชื่อ Sheet ออกมาครับ

protected void Page_Load(object sender, EventArgs e)
    {
        GetExcelSheetNames("C:\\test.xls");
    }
    private String[] GetExcelSheetNames(string excelFile)
    {
        OleDbConnection objConn = null;
        System.Data.DataTable dt = null;

        try
        {
            // Connection String. Change the excel file to the file you
            // will search.
            String connString = "Provider=Microsoft.Jet.OLEDB.4.0;" +
                "Data Source=" + excelFile + ";Extended Properties=Excel 8.0;";
            // Create connection object by using the preceding connection string.
            objConn = new OleDbConnection(connString);
            // Open connection with the database.
            objConn.Open();
            // Get the data table containg the schema guid.
            dt = objConn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

            if (dt == null)
            {
                return null;
            }

            String[] excelSheets = new String[dt.Rows.Count];
            int i = 0;

            // Add the sheet name to the string array.
            foreach (DataRow row in dt.Rows)
            {
                excelSheets[i] = row["TABLE_NAME"].ToString();
                DropDownList1.Items.Add(row["TABLE_NAME"].ToString());
                i++;
            }

        

            return excelSheets;
           
        }
        catch (Exception ex)
        {
            return null;
        }
        finally
        {
            // Clean up.
            if (objConn != null)
            {
                objConn.Close();
                objConn.Dispose();
            }
            if (dt != null)
            {
                dt.Dispose();
            }
        }
    }

        private List<string> GetExcelSheetNames()
        {
            DataTable dt = null;

            try
            {
                if (conn.State == ConnectionState.Open) conn.Close();
                conn.Open();

                // Get the data table containg the schema guid.
                dt = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, null);

                if (dt == null)
                {
                    return null;
                }

                List<string> excelSheets = new List<string>(dt.Rows.Count);
                int i = 0;

                foreach (DataRow row in dt.Rows)
                {
                    if (row["TABLE_NAME"].ToString().Contains("$"))//checks whether row contains '_xlnm#_FilterDatabase' or sheet name(i.e. sheet name always ends with $ sign)
                    {
                        if (row["TABLE_NAME"] != null)
                        {
                            excelSheets.Add(GetSheetName(row["TABLE_NAME"].ToString()));
                        }
                    }
                    i++;
                }

                excelSheets = excelSheets.Distinct().ToList();

                return excelSheets;
            }
            catch (Exception ex)
            {
                return null;
            }
        }
        private string GetSheetName(string str)
        {
            int use = 0;
            int len = str.Length;

            // Find last position of "$"
            for (int i = 0; i < len; i++)
            {
                if (str.Substring(i, 1) == "$") use = i;
            }

            string tmp;
            if (use == 0)
            { tmp = str; }
            else
            { tmp = str.Substring(0, use + 1); }
            return tmp;
        }

Private Function GetExcelSheetNames() As List(Of String)
	Dim dt As DataTable = Nothing

	Try
		If conn.State = ConnectionState.Open Then
			conn.Close()
		End If
		conn.Open()

		' Get the data table containg the schema guid.
		dt = conn.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, Nothing)

		If dt Is Nothing Then
			Return Nothing
		End If

		Dim excelSheets As New List(Of String)(dt.Rows.Count)
		Dim i As Integer = 0

		For Each row As DataRow In dt.Rows
			If row("TABLE_NAME").ToString().Contains("$") Then
				'checks whether row contains '_xlnm#_FilterDatabase' or sheet name(i.e. sheet name always ends with $ sign)
				If row("TABLE_NAME") IsNot Nothing Then
					excelSheets.Add(GetSheetName(row("TABLE_NAME").ToString()))
				End If
			End If
			i += 1
		Next

		excelSheets = excelSheets.Distinct().ToList()

		Return excelSheets
	Catch ex As Exception
		Return Nothing
	End Try
End Function
Private Function GetSheetName(str As String) As String
	Dim use As Integer = 0
	Dim len As Integer = str.Length

	' Find last position of "$"
	For i As Integer = 0 To len - 1
		If str.Substring(i, 1) = "$" Then
			use = i
		End If
	Next

	Dim tmp As String
	If use = 0 Then
		tmp = str
	Else
		tmp = str.Substring(0, use + 1)
	End If
	Return tmp
End Function