Can't add DataRow to DataTable

gib99 · Jan 15, 2014

Hello,

I'm having trouble adding a DataRow to a DataTable.

I create the DataRow like so:

DataRow row = myDataTable.NewRow();

I add things to the row, then I try to add the row back to the table:

myDataTable.Rows.Add(row);

It tells me: "This row already belongs to this table."

Ironically, if I try:

row.AcceptChanges();

it tells me: "Cannot perform this operation on a row not in the table."

so is it in the table or is it not?

myDataTable.AcceptChanges() seems to run without any exceptions, but my table is still empty.

What gives?

Moregelen · Jan 16, 2014

Do you have a primary key set on the table? If you do, you could have a duplicate.

I'm using this in one of my standard libraries without any problems. .NET 2.0.

Code:

[COLOR=#2B91AF]DataRow[/color] tempRow;
[COLOR=#0000FF]while[/color] (DbDataReader.Read())
{
    tempRow = tempTable.NewRow();
    [COLOR=#0000FF]for[/color] ([COLOR=#0000FF]int[/color] i = 0; i &lt; DbDataReader.FieldCount; i++)
        tempRow&#91;i&#93; = DbDataReader&#91;i&#93;;
    tempTable.Rows.Add(tempRow);
}
[COLOR=#0000FF]return[/color] tempTable;

You could always try this instead when adding the row to the table:

Code:

myDataTable.ImportRow(row);

and see if that works.

gib99 · Jan 16, 2014

Thanks Moregelen,

I solved the problem by adding the row right after creating it.

At first, I had this:

DataRow row = myDataTable.NewRow();
row[1] = x;
row[2] = y;
row[3] = z;
myDataTable.Rows.Add(row);

But now I have this:

DataRow row = myDataTable.NewRow();
myDataTable.Rows.Add(row);
row[1] = x;
row[2] = y;
row[3] = z;

The latter seems to work.

Moregelen · Jan 16, 2014

Very strange.

obislavu · Feb 24, 2014

Solution 1:
<code>
DataRow row = dt.NewRow();
row[0] = "maria";
row[1] = "george";
dt.Rows.Add(row);
// row = dt.NewRow();
row[0] = "Helene";
row[1] = "Maxim";
dt.Rows.Add(row);
</code>
Running the above you get ""This row already belongs to this table."
Uncomment the comments and the second row is added.
Reason: In fact
<cde>
row[0] = "Helene";
row[1] = "Maxim";
</code>
modify the previous values of the same "row" object.

Solution 2:
<code>
DataRow row = dt.NewRow();
row[0] = "maria";
row[1] = "george";
dt.Rows.Add(row); // or dt.ImportRow(row);
row[0] = "Helene";
row[1] = "Maxim";
dt.ImportRow(row);

row[0] = "Christina";
row[1] = "Bill";
dt.ImportRow(row);
</code>
Explanation:
Rows.Add(dr) - add a reference of te dr DataRow object
Rows.ImportRow(dr) - add a copy of the dr DataRow object

obislavu

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Can't add DataRow to DataTable

gib99

Programmer

Moregelen

Programmer

gib99

Programmer

Moregelen

Programmer

obislavu

Programmer

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