How to store column name as first row in datatable?

Question

Title| 11/09/2015 | 23/01/2015
----  -------------  ----------------
 A        1             12  
 B        1             13

I want to store the column name as Datarow in DataTable.

Tried :

DataRow firstRow = table.NewRow();
for (var i = 0; i < table.Columns.Count; i++)
{        
     firstRow[i] = header.Rows[0][i].ToString();
}
table.Rows.InsertAt(firstRow, 0);

Error:

Incorrect String 11/09/2015 need double.

Expected Output:

 Title| 11/09/2015 | 23/01/2015
----  -------------  ----------------
Title   11/09/2015   23/01/2015
 A        1             12  
 B        1             13

Try for (var i = 0; i < table.Columns.Count - 1; i++) and declare your column as string so it can hold any value — Oscar, Dec 11 '15 at 08:57
Yes tried , i know , the problem in casting , DataRow doesnot accept column name as string i guess :) — vinodh, Dec 11 '15 at 08:58
As your table has columns of different types, you simply cannot do this. What is the need to do this? It sounds senseless. — Yeldar Kurmangaliyev, Dec 11 '15 at 08:59
You can use [`DataColumn.ColumnName property`](https://msdn.microsoft.com/en-us/library/system.data.datacolumn.columnname.aspx). Check [How do I get column names to print in this C# program?](http://stackoverflow.com/q/2557937/447156) as well. — Soner Gönül, Dec 11 '15 at 08:59
Can i ask why you want to add the columns to the first `DataRow`? You have the informations already in the table. — Tim Schmelter, Dec 11 '15 at 09:00
yeah i know @yeldar i dont know how to do that that's why i posted :) — vinodh, Dec 11 '15 at 09:02
@vinodh: your expected output is not what you describe. I thought you want the column-names in the first row. Can you explain better what you want? Where do you get that error? — Tim Schmelter, Dec 11 '15 at 09:03
Sorry for Confusion @Tim . I need first row as my columnname .. Thats it. But problem is format , Datarow couldn't understand the dateformat . Even i tried to change to string i unable store the Columnname as row. — vinodh, Dec 11 '15 at 09:06
First row as your column name? You know that a `DataRow` can have n-field values. So why do you use singular " column name" instead of " column names"? — Tim Schmelter, Dec 11 '15 at 09:08
@vinodh: now i understand the problem. The second and third columns are `double`-columns. Of course you can'd add values like `11/09/2015`. How would you want to convert that to double? You etiehr have to tell us how you want toconvert it or use `String` as DataColumn-type — Tim Schmelter, Dec 11 '15 at 09:13

Mairaj Ahmad · Answer 1 · 2015-12-11T09:05:12.180

1

Try this

DataRow dr = table.NewRow();
foreach (DataColumn dc in table.Columns)
 {

  dr[dc] = dc.ColumnName;

 }
table.Rows.InsertAt(dr, 0);

edited Dec 11 '15 at 09:05

answered Dec 11 '15 at 09:04

Mairaj Ahmad

14,434
2
26
40

1

I thought that also, but look at his expected output. – Tim Schmelter Dec 11 '15 at 09:04
I tried this i guess this would produce expected output. – Mairaj Ahmad Dec 11 '15 at 09:05
Thanks for your answer. Normally it should work but in someways we have problem in column Datatype. +1 for right answer... but @tim explained good and futuristic way that's why accepted his answer. – vinodh Dec 11 '15 at 09:54
1

Yes he is a genius guy his asnwer is much clearer than mine. – Mairaj Ahmad Dec 11 '15 at 09:58

Tim Schmelter · Accepted Answer · 2015-12-11T09:24:12.957

Now i understand the problem. The second and third columns are double-columns. Of course you can'd add values like 11/09/2015. How would you want to convert that to double? You either have to tell us how you want to convert it or use String as DataColumn-type.

One option would be to use DateTime.ToOADate() which is the ole automation date:

DataRow firstRow = table.NewRow();
for (var i = 0; i < table.Columns.Count; i++)
{
    string colName = table.Columns[i].ColumnName;
    DateTime dt;
    double d;
    if(DateTime.TryParse(colName, out dt))
        firstRow.SetField(i, dt.ToOADate());
    else if(double.TryParse(colName, out d))
        firstRow.SetField(i, d);
}
table.Rows.InsertAt(firstRow, 0);

Another way would be to check the column-type:

DataRow firstRow = table.NewRow();
for (var i = 0; i < table.Columns.Count; i++)
{
    DataColumn col = table.Columns[i];
    if (col.DataType == typeof(string))
    {
        firstRow.SetField(i, col.ColumnName);
    }
    else if (col.DataType == typeof(DateTime))
    {
        DateTime dt;
        if (DateTime.TryParse(col.ColumnName, out dt))
            firstRow.SetField(i, dt);
    }
    else if (col.DataType == typeof(double))
    {
        double d;
        if (double.TryParse(col.ColumnName, out d))
            firstRow.SetField(i, d);
    }
}
table.Rows.InsertAt(firstRow, 0);

But this natural approach would not solve your issue since you have a DateTime value that has to be converted to a double.

The third and easiest approach would be use use String as column-type.

DataTable table = new DataTable();
table.Columns.Add("Title");
table.Columns.Add("11/09/2015"); // string is default
table.Columns.Add("23/01/2015");
DataRow firstRow = table.NewRow();
for (var i = 0; i < table.Columns.Count; i++)
{
    string colName = table.Columns[i].ColumnName;
    firstRow.SetField(i, colName);
}
table.Rows.InsertAt(firstRow, 0);

That works always.

i hope it will works, i miss the setField property... :) I ll check — vinodh, Dec 11 '15 at 09:28
@vinodh: `SetField` is just another method to assign a value. You could also use firstRow[i] = new value. The difference is that `SetField` also supports nullable types. — Tim Schmelter, Dec 11 '15 at 09:31
Thanks for your detailed answer.. i can debug now ... final question **Input string was not in a correct format.Couldn't store <1/2/2015> in 1/2/2015 Column. Expected type is Double.** Its giving this error i can debug... but you can easily found the error thats y i posted here. — vinodh, Dec 11 '15 at 09:37
@vinodh: with what approach? Since expected type is double i think you haven't used the third. How do you create the table and the columns? — Tim Schmelter, Dec 11 '15 at 09:39
@vinodh: How do you create the table? The last way uses `string` as column-type, so it's not clear how it can expect double. The second approach also checks if the column-type mateches the value, so if it can't be parsed it will use `DBNull.Value` — Tim Schmelter, Dec 11 '15 at 09:41
Let us [continue this discussion in chat](http://chat.stackoverflow.com/rooms/97603/discussion-between-vinodh-and-tim-schmelter). — vinodh, Dec 11 '15 at 09:43

How to store column name as first row in datatable?

2 Answers2