c#获取excel时不要创建列,直接导入现有列

string strConn = "Provider=Microsoft.Jet.OLEDB.4.0;Data Source=E:\\业务表.xls;Extended Properties=Excel 8.0";
DataSet ds = new DataSet();
OleDbDataAdapter oada = new OleDbDataAdapter("select 日期,地点,整日或半日,日结工资 from [" + dataGridView1.CurrentRow.Cells["Column1"].Value.ToString() + "$]", strConn);
oada.Fill(ds);
dataGridView3.DataSource = ds.Tables[0];

DataTable schemaTable = conn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, null);
string tname = schemaTable.Rows[num][2].ToString().Trim();//获取页面标题
OleDbDataAdapter odda = new OleDbDataAdapter(string.Format("select * from [{0}]", tname), conn);

datetime time = datetime.fromoadate(41019);