excel表中有大约三万条记录，每次都从excel中查询费时较长，读入内存 再用linqtodatatable进行过滤查找
private void button2_Click(object sender, EventArgs e){string excelFilePath = @"C:\dd.xls";string excelSheetName = @"medpinyin";tb = GetExcelTableByOleDB(excelFilePath, excelSheetName);}private void button4_Click(object sender, EventArgs e){EnumerableRowCollection<DataRow>kk =tb.AsEnumerable().Where(A => A.Field<string>("medpy").StartsWith("ZYMP"));ArrayList al = new ArrayList();foreach (var q in kk){if (!al.Contains(q["medname"].ToString())){al.Add(q["medname"].ToString());}}string[] s = (string[])al.ToArray(typeof(string));MessageBox.Show(s[0]);MessageBox.Show(kk.Count().ToString());}/// <summary>/// 读取Excel中数据/// </summary>/// <param name="strExcelPath"></param>/// <param name="tableName"></param>/// <returns></returns>public static DataTable GetExcelTableByOleDB(string strExcelPath, string tableName){try{DataTable dtExcel = new DataTable();//数据表DataSet ds = new DataSet();//获取文件扩展名string strExtension = System.IO.Path.GetExtension(strExcelPath);string strFileName = System.IO.Path.GetFileName(strExcelPath);//Excel的连接OleDbConnection objConn = null;switch (strExtension){case ".xls":objConn = new OleDbConnection("Provider=Microsoft.Jet.OLEDB.4.0;Data Source=" + strExcelPath + ";" + "Extended Properties=\"Excel 8.0;HDR=yes;IMEX=1;\"");break;case ".xlsx":objConn = new OleDbConnection("Provider=Microsoft.ACE.OLEDB.12.0;Data Source=" + strExcelPath + ";" + "Extended Properties=\"Excel 12.0;HDR=yes;IMEX=1;\"");//此连接可以操作.xls与.xlsx文件 (支持Excel2003 和 Excel2007 的连接字符串) 备注： "HDR=yes;"是说Excel文件的第一行是列名而不是数，"HDR=No;"正好与前面的相反。"IMEX=1 "如果列中的数据类型不一致，使用"IMEX=1"可必免数据类型冲突。 break;default:objConn = null;break;}if (objConn == null){return null;}objConn.Open();//获取Excel中所有Sheet表的信息//System.Data.DataTable schemaTable = objConn.GetOleDbSchemaTable(System.Data.OleDb.OleDbSchemaGuid.Tables, null);//获取Excel的第一个Sheet表名// string tableName1 = schemaTable.Rows[0][2].ToString().Trim();string strSql = "select * from [" + tableName + "$] ";//获取Excel指定Sheet表中的信息OleDbCommand objCmd = new OleDbCommand(strSql, objConn);OleDbDataAdapter myData = new OleDbDataAdapter(strSql, objConn);myData.Fill(ds, tableName);//填充数据objConn.Close();//dtExcel即为excel文件中指定表中存储的信息dtExcel = ds.Tables[tableName];MessageBox.Show(dtExcel.Rows.Count.ToString());return dtExcel;}catch (Exception ex){//Console.WriteLine(ex.Message + "\r\n" + ex.StackTrace);MessageBox.Show(ex.Message + "\r\n" + ex.StackTrace);return null;}}