如何使用for循环一次读取一个csv文件？ [英] how to use for loop to read csv file one at a time?

问题描述

  string  todate = txtToDate1.Text; 
  string  fromtime = DropDownList2.SelectedItem.Text; 
  string  totime = DropDownList3.SelectedItem.Text; 
 
  string  fromdatetime = fromdate +   _ + fromtime; 
  string  todatetime = todate +   _  + totime; 
 
 
 con.ConnectionString = constr; 
 
  //  为命令对象创建实例 
 OleDbCommand cmd =  new  OleDbCommand（）; 
 
 
 cmd.Connection = con; 
  //  在以下查询中设置您的文件名 
 cmd.CommandText =   select * from + fromdatetime +  。csv; 
 
 
 
  //  打开Oledb连接以读取CSV文件 
 con.Open（）; 
 
  //  创建一个数据表来存储CSV文件中的数据 
 DataTable dt =  new  DataTable（）; 
 
  //  将数据加载到数据表中 
 dt.Load （cmd.ExecuteReader（））; 

string fromdatetime is像12162013_0730.csv和字符串todatetime之类的东西就像12162013_0930.csv ...我如何使用for循环来读取fromdatetime todatetime之间的文件...阅读12162013_0730.csv，12162013_0830.csv，12162013_0930.csv，一个文件一次。

解决方案

您好b $ b这可能对您有帮助..

  string  strfrom =    12162013_0730; 
  string  strto =   12162013_1030; 
 
  var  来自 = DateTime.ParseExact（strfrom，  MMddyyyy_hhmm，CultureInfo.InvariantCulture）; 
  var  to = DateTime.ParseExact（strto，  MMddyyyy_hhmm，CultureInfo.InvariantCulture）; 
  double  interval =  60 ; 
 List< string> lstDateString =  new  List< string>（）; 
 lstDateString.Add（strfrom）; 
  while （ from  .AddMinutes（interval）！= to）
 {
 
 lstDateString.Add（ from  .AddMinutes（interval）.ToString（ < span class =code-string> MMddyyyy_hhmm））; 
 interval = interval +  60 ; 
} 
 lstDateString.Add（strto）; 
 
  foreach （ string  datestring  in  lstDateString）
 {
  string  csv = datestring +  。csv; 
  //  您的编码在这里..  
} 

string todate = txtToDate1.Text;
                string fromtime = DropDownList2.SelectedItem.Text;
                string totime = DropDownList3.SelectedItem.Text;

                string fromdatetime = fromdate + "_" + fromtime;
                string todatetime = todate + "_" + totime;

            
                con.ConnectionString = constr;

                //create instance for command object 
                OleDbCommand cmd = new OleDbCommand();
               

                cmd.Connection = con;   
                // set your file name in the below query
                cmd.CommandText = "select * from " + fromdatetime + ".csv ";
               
                
  
                //Open Oledb Connection to read CSV file 
                con.Open(); 

                //Create one datatable to store data from CSV file
                DataTable dt = new DataTable();

                // Load Data into the datatable 
                dt.Load(cmd.ExecuteReader());

string fromdatetime is something like 12162013_0730.csv and string todatetime is something like 12162013_0930.csv...how can i use for loop to read the file in between the fromdatetime todatetime... read 12162013_0730.csv ,12162013_0830.csv,12162013_0930.csv, one file at a time.

解决方案

Hi This might help you..

string strfrom = "12162013_0730";
        string strto = "12162013_1030";

       var from =  DateTime.ParseExact(strfrom, "MMddyyyy_hhmm", CultureInfo.InvariantCulture);
       var to = DateTime.ParseExact(strto, "MMddyyyy_hhmm", CultureInfo.InvariantCulture);
       double interval  = 60;
       List<string> lstDateString = new List<string>();
       lstDateString.Add(strfrom);
       while (from.AddMinutes(interval) != to)
       {

           lstDateString.Add(from.AddMinutes(interval).ToString("MMddyyyy_hhmm"));
           interval = interval + 60;
       }
       lstDateString.Add(strto);

       foreach (string datestring in lstDateString)
       {
           string csv = datestring + ".csv";
           // your coding here..
       }

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