从Excel读数据，有时候会读出空的字符串

connectString = "Provider = Microsoft.Jet.OLEDB.4.0;Data Source = '"
                         + templateName + "';Extended Properties = 'Excel 8.0;HDR=YES;IMEX=1;'";

                    excelOleDBConnection = new OleDbConnection(connectString);
                    excelOleDBCommand = new OleDbCommand("SELECT * FROM [" + sheetName + "$]", excelOleDBConnection);
                    excelOleDBDataAdapter = new OleDbDataAdapter(excelOleDBCommand);

                    excelOleDBDataAdapter.Fill(templetData);
                    excelOleDBCommand.Dispose();
                    excelOleDBDataAdapter.Dispose();

记得设置 IMEX=1，否则会有可能对默写混合类型的数据读出来是空的情况

HDR=Yes/No

可选参数，指定 Excel 表的第一行是否列名，缺省为 Yes，可以在注册表中修改缺省的行为。

IMEX=1

可选参数，将 Excel 表中混合 Intermixed 数据类型的列强制解析为文本

 

HDR=Yes;" indicates that the first row contains columnnames, not data. "HDR=No;" indicates the opposite. 
"IMEX=1;" tells the driver to always read "intermixed" (numbers, dates, strings etc) data columns as text. Note that this option might affect excel sheet write access negative.