用OLEDB通过设置连接字符串可以像读取sqlserver一样将excel中的数据读取出来，但是excel2003和excel2007/2010的连接字符串是不同的
/// <summary>
    /// 把数据从Excel装载到DataTable
    /// </summary>
    /// <param name="pathName">带路径的Excel文件名</param>
    /// <param name="sheetName">工作表名</param>
    /// <param name="tbContainer">将数据存入的DataTable</param>
    /// <returns></returns>
    public DataTable ExcelToDataTable(string pathName, string sheetName)
    {
        DataTable tbContainer = new DataTable();
        string strConn = string.Empty;
        if (string.IsNullOrEmpty(sheetName)) { sheetName = "Sheet1"; }
        FileInfo file = new FileInfo(pathName);
        if (!file.Exists) { throw new Exception("文件不存在"); }
        string extension = file.Extension;
        switch (extension)
        {
            case ".xls":
                strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathName + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";
                break;
            case ".xlsx":
                strConn = "Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + pathName + ";Extended Properties='Excel 12.0;HDR=Yes;IMEX=1;'";
                break;
            default:
                strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + pathName + ";Extended Properties='Excel 8.0;HDR=Yes;IMEX=1;'";
                break;
        }
        //链接Excel
        OleDbConnection cnnxls = new OleDbConnection(strConn);
        //读取Excel里面有 表Sheet1
        OleDbDataAdapter oda = new OleDbDataAdapter(string.Format("select * from [{0}$]", sheetName), cnnxls);
        DataSet ds = new DataSet();
        //将Excel里面有表内容装载到内存表中！
        oda.Fill(tbContainer);
        return tbContainer;
    }
这里需要注意的地方是，当文件的后缀名为.xlsx(excel2007/2010)时的连接字符串是"Provider=Microsoft.ACE.OLEDB.12.0;...."，注意中间红色部分不是"Jet"。