如何快速从DataTable删除DataRow

Question

I input data in DataTable in column direction.

for(int i=0 ; i<mTable.Count ; i++){
  Table.Columns.Add(i);
  foreach(DataRow row in Table.Rows){
    if(result == 1)
      row[i] = result;
    else
      row[i] = null;
  }
}

From here, If All data of column is null, I want to delete row.

For example,

1 2 3 4 5

6 7 8 9 10

11 12 13 14 15

16 17 18 19 20

11, 12, 13, 14, 15 are null, I want to delete Table.Rows[2].

So, I use next way.

for(int i = Table.Rows.Count-1;i >= 0;i--)
{
                for (int j = 0; j < mTable.Count; j++)
                {
                    if (Table.Rows[i][j] != null)
                        break;
                    if(j == mTable.Count-1)
                        Table.Rows.Remove(Table.Rows[i]);
                }
}

But, If There's a lot of data, It will slow down considerably.

Is there another fast way?

Answer 1

You algorithm is probably the quickest method. But you can can a little bit better performance with a few improvements

            int numberOfCols = Table.Columns.Count;
            for (int i = Table.Rows.Count - 1; i >= 0; i--)
            {
                Boolean delete = true;
                for (int j = 0; j < numberOfCols; j++)
                {
                    if (Table.Rows[i][j] != null)
                    {
                        delete = false;
                        break;
                    }
                }
                if (delete)
                {
                    Table.Rows.Remove(Table.Rows[i]);
                }
            }

Answer 2

Instead of deleting the rows, you can select the non null rows from your table.

public void DtSelect()
    {
        var dt = new DataTable();
        var columns = Enumerable.Range(1, 10).Select(x => "Col" + x).ToList();
        columns.ForEach(x => dt.Columns.Add(x));
        Enumerable.Range(1, 1000).ToList().ForEach(x =>
         {
             var row = dt.NewRow();
             if (x % 15 == 0) columns.ForEach(z => row[z] = x);
             dt.Rows.Add(row);
         });
         var query =  "(" + string.Join(" is not null) or (", columns) + " is not null)";

        var nonEmpty = dt.Select(query).CopyToDataTable();


    }

nonEmpty will not be a datatable with all rows that are non empty;