在数据表中添加新行时,向数据表列添加逗号分隔值的更好方法

将各个列值放入列表中,然后用 String.Join :

var dt = new DataTable();

var data=Helper.GetData();

 foreach (DataRow dr in data)
 {
      List<string> values = new List<string>();
      DataRow dr = dt.NewRow();

      var columns=Helper.GetColumns();

      foreach(var item in columns)
      {
          dr["Id"] = dr[item].ToString();
          values.Add(dr[item].ToString());
      }
      dr["Col1"] = string.Join(",", values);
 } 

我承认对为什么要覆盖“Id”列有点困惑,但上面的代码应该与最初发布的代码具有相同的效果。

如果我明白你想要什么,这里有一个简单的例子:

DataTable dt = new DataTable("SO Example");

dt.Columns.Add("A", typeof(int));
dt.Columns.Add("B", typeof(string));
dt.Columns.Add("C", typeof(string));
dt.Columns.Add("D", typeof(string));
dt.Columns.Add("Concatenation", typeof(string));

dt.Rows.Add(1, "bbbbbb", "tra la la", "d");
dt.Rows.Add(2, "b b b", "tttt", "dddddd");
dt.Rows.Add(3, "b-b-b-b-b-b", "C", "d.d.d.d.d.d");
dt.Rows.Add(4, "bBbBbBb", "CCC", "dd");
dt.Rows.Add(5, "B", "C", "D");

foreach (DataRow row in dt.Rows)
{
    row["Concatenation"] = string.Join(", ", row.ItemArray.Take(row.ItemArray.Length - 1));
}

表格:

输出:

我想是的 Veverke 答案表明绝对是最适合你的解决方案。 我刚刚尝试将你的代码集成到他的解决方案中。。。

var dt = new DataTable();
var data=Helper.GetData();
foreach (DataRow drSrc in data) //changed from "dr" in "drSrc" to readability (further, compiler should rises a syntax error)
{
   DataRow dr = dt.NewRow();

   dr["id"] = drSrc[drSrc.ItemArray.Length - 2]; //the last value of drSrc (after clarifications in comments and chat..)
   dr["Col1"]  = string.Join(", ", drSrc.ItemArray.Take (drSrc.ItemArray.Length - 1));

   dt.Rows.Add(dr);  //it missed in your code, but I suppose you want add it into the datatable 
}