Merge 2 DataTables and store in a new one

If I have 2 DataTables (dtOne and dtTwo) and I want to merge them and put them in another DataTable (dtAll). How can I do this in C#? I tried the Merge statement on the datatable, but this returns void. Does Merge preserve the data? For example, if I do:

 dtOne.Merge(dtTwo);

Does dtOne change or does dtTwo change and if either one changes, do the changes preserve?

I know I can't do this because Merge returns void, but I want to be able to store the Merger of both dtOne and dtTwo in dtAll:

//Will Not work, How do I do this
dtAll = dtOne.Merge(dtTwo);

The Merge method takes the values from the second table and merges them in with the first table, so the first will now hold the values from both.

If you want to preserve both of the original tables, you could copy the original first, then merge:

dtAll = dtOne.Copy();
dtAll.Merge(dtTwo);

Instead of dtAll = dtOne.Copy(); in Jeromy Irvine's answer you can start with an empty DataTable and merge one-by-one iteratively:

dtAll = new DataTable();
...
dtAll.Merge(dtOne);
dtAll.Merge(dtTwo);
dtAll.Merge(dtThree);
...

and so on.

This technique is useful in a loop where you want to iteratively merge data tables:

DataTable dtAllItems = new DataTable();

foreach(var item in items)
{
    DataTable dtItem = getDataTable(item); // some function that returns a data table
    dtAllItems.Merge(dtItem);
}

dtAll = dtOne.Copy();
dtAll.Merge(dtTwo,true);

The parameter TRUE preserve the changes.

For more details refer to MSDN.

DataTable dtAll = new DataTable();
DataTable dt= new DataTable();
foreach (int id in lst)
{
    dt.Merge(GetDataTableByID(id)); // Get Data Methode return DataTable
}
dtAll = dt;

This is what i did for merging two datatables and bind the final result to the gridview

        DataTable dtTemp=new DataTable();
        for (int k = 0; k < GridView2.Rows.Count; k++)
        {
            string roomno = GridView2.Rows[k].Cells[1].Text;
            DataTable dtx = GetRoomDetails(chk, roomno, out msg);
            if (dtx.Rows.Count > 0)
            {
                dtTemp.Merge(dtx);
                dtTemp.AcceptChanges();
              
            }
        }