#region 读取导入Excel数据    /// <summary>    ///     /// </summary>    /// <param name="filename"></param>    /// <param name="fields"></param>    /// <returns></returns>    public DataSet ReadDataFromExcel(string filename, string fields)    {        DataSet ds = new DataSet();        try        {            string cnn = string.Empty;            string ext = Path.GetExtension(filename).ToLower();            if (ext == ".xls")            {                cnn = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source = " + filename + ";Extended Properties=" + (char)34 + "Excel 8.0;HDR=Yes;IMEX=1;" + (char)34;            }            else if (ext == ".xlsx")            {                cnn = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source = " + filename + ";Extended Properties=" + (char)34 + "Excel 12.0;HDR=Yes;IMEX=1;" + (char)34;            }            else            {                throw new Exception("读取失败，非excel文件格式。");            }            using (OleDbConnection connection = new OleDbConnection(cnn))            {                connection.Open();                DataTable tables = connection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });                foreach (DataRow row in tables.Rows)                {                    string table = row["TABLE_NAME"].ToString();                    DataTable dt = ReadEachExcelSheetData(connection, table, fields);                    if (dt != null)                    {                        ds.Tables.Add(dt.Copy());                    }                }            }            return ds;        }        catch (Exception ex)        {            throw new Exception("数据文件或者内容格式有严重错误(" + ex.Message + ")，请检查！");        }    }    public DataTable ReadEachExcelSheetData(OleDbConnection connection, string table, string fields)    {        try        {            string sql = string.Empty;            string query = string.Empty;            if (fields.IndexOf(‘,‘) > 0)            {                foreach (string column in fields.Split(‘,‘))                {                    query += "[" + column + "],";                }                query = query.Trim(‘,‘);            }            else            {                query = fields;            }            sql = @"                        SELECT                                 {0}                        FROM                                 [{1}]                        ";            sql = string.Format(sql, query, table);            DataSet ds = new DataSet();            OleDbDataAdapter adapter = new OleDbDataAdapter(sql, connection);            adapter.Fill(ds, table);            if (ds != null && ds.Tables.Count > 0 && ds.Tables[0].Rows.Count > 0)            {                return ds.Tables[0];            }        }        catch (Exception ex)        {            throw ex;        }        return null;    }    private DataSet GetDataFromExcel(string filename,string fields)    {        DataSet ds = new DataSet();        string cnn = string.Empty;        string ext = Path.GetExtension(filename).ToLower();        if (ext == ".xls")        {            cnn = "Provider = Microsoft.Jet.OLEDB.4.0; Data Source = " + filename + ";Extended Properties=" + (char)34 + "Excel 8.0;HDR=Yes;IMEX=1;" + (char)34;        }        else if (ext == ".xlsx")        {            cnn = "Provider = Microsoft.ACE.OLEDB.12.0; Data Source = " + filename + ";Extended Properties=" + (char)34 + "Excel 12.0;HDR=Yes;IMEX=1;" + (char)34;        }        else        {            throw new Exception("读取失败，非excel文件格式。");        }        using (OleDbConnection connection = new OleDbConnection(cnn))        {            connection.Open();            DataTable tables = connection.GetOleDbSchemaTable(OleDbSchemaGuid.Tables, new object[] { null, null, null, "TABLE" });            string tableName = tables.Rows[0]["TABLE_NAME"].ToString();            string sql = "select * from [{0}]";            sql = string.Format(sql, tableName);            OleDbCommand command = connection.CreateCommand();            command.CommandText = sql;            OleDbDataAdapter adapter = new OleDbDataAdapter(command);            adapter.Fill(ds);            return ds;        }    }    #endregion