Copying data of only few columns to one more data

问题:

I have a scenario where I get a data table with 65 columns and 100 rows. I need to create one more data table with all 100 rows, i.e. the same as the original data table but should be having only 5 columns out of 65 present in original table. Is there any way to achieve this without looping?

回答1:

Try DataView.ToTable method.

Use it like this:

DataTable newTable = oldTable.DefaultView.ToTable(false, "ColumnName1", "ColumnName2", "ColumnName3", "ColumnName4", "ColumnName5"); 

回答2:

DataTable oldTable = new DataTable();
DataTable newTable = oldTable.Copy();
for (int i = 5; i < 65; i++)
{
    newTable.Columns.RemoveAt(i);   
}

回答3:

Try like this,

DataTable newTable  = oldTable.Copy();
newTable.Columns.Remove("ColumnName");

You remove the unwanted columns here.

Here is the best Solution for your Question:

DataTable dt = new DataTable();
string [] column = {"Column1", "Column2"};
dt = DTItem.DefaultView.ToTable("dd", false, column);      
//DTItem is the Existing  Table and "dd" is the temporary tablename, u give whatever u want

回答4:

    private void button3_Click(object sender, EventArgs e)
    {
        DataTable destiny = new DataTable();
        destiny.Columns.Add("c1");
        destiny.Columns.Add("c2");
        destiny.Columns.Add("c3");
        destiny.Columns.Add("c4");

        CopyColumns(dtST_Split, destiny, "c1", "c2","c3","c4");

    }

    private void CopyColumns(DataTable source, DataTable dest, params string[] columns)
    {
        foreach (DataRow sourcerow in source.Rows)
        {
            DataRow destRow = dest.NewRow();
            foreach (string colname in columns)
            {
                destRow[colname] = sourcerow[colname];
            }
            dest.Rows.Add(destRow);
        }
    }