Question

what would be the best way to compare two data table. i populate two data table reading two different xml and now i need to compare and return the difference in terms of datatable.my compare logic was

private DataTable CompareDataTables(DataTable dtFirst, DataTable dtSecond)
    {
        int result = 0;
        bool flag = false;
        DataTable dtNoRows = new DataTable();
        dtNoRows.Columns.Add("Result");

        DataTable dtDiff = new DataTable();
        dtDiff.Columns.Add("Field Name");
        dtDiff.Columns.Add("Old Value");
        dtDiff.Columns.Add("New Value");
        DataRow dr = null;
        if (dtFirst.Columns.Count == dtSecond.Columns.Count)
        {
            for (int i = 0; i <= dtFirst.Columns.Count - 1; i++)
            {
                try
                {
                    DateTime.Parse(dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString().Trim());
                    flag = true;
                }
                catch (Exception ex)
                {
                    flag = false;
                }

                if (!flag)
                {
                    if (dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString().Trim().ToUpper() != dtSecond.Rows[0][dtSecond.Columns[i].ColumnName.ToString()].ToString().Trim().ToUpper())
                    {
                        dr = dtDiff.NewRow();
                        dr["Field Name"] = dtFirst.Columns[i].ColumnName.ToString();
                        dr["Old Value"] = dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString().Trim();
                        dr["New Value"] = dtSecond.Rows[0][dtSecond.Columns[i].ColumnName.ToString()].ToString().Trim();
                        dtDiff.Rows.Add(dr);
                    }
                }
                else
                {
                    result = DateTime.Compare(DateTime.Parse(dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString()), DateTime.Parse(dtSecond.Rows[0][dtSecond.Columns[i].ColumnName.ToString()].ToString()));
                    if (result != 0)
                    {
                        dr = dtDiff.NewRow();
                        dr["Field Name"] = dtFirst.Columns[i].ColumnName.ToString();
                        dr["Old Value"] = DateTime.Parse(dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString().Trim()).ToString("MM/dd/yyyy") + " - " + DateTime.Parse(dtFirst.Rows[0][dtFirst.Columns[i].ColumnName.ToString()].ToString().Trim()).ToString("hh:mm:ss");
                        dr["New Value"] = DateTime.Parse(dtSecond.Rows[0][dtSecond.Columns[i].ColumnName.ToString()].ToString().Trim()).ToString("MM/dd/yyyy") + " - " + DateTime.Parse(dtSecond.Rows[0][dtSecond.Columns[i].ColumnName.ToString()].ToString().Trim()).ToString("hh:mm:ss");
                        dtDiff.Rows.Add(dr);

                    }
                    flag = false;
                }
            }
        }
        return dtDiff;
    }

my code is working fine but i need to the is there any best way out. please guide me.

Answer 1

you can use LINQ to comparing tables values(two table must have the same structure)

bool flag = false;
if (dtFirst.Columns.Count == dtSecond.Columns.Count)
{
    for (int i = 0; i <= dtFirst.Columns.Count - 1; i++)
    {
        String colName = dtFirst.Columns[i].ColumnName;
        var colDataType = dtFirst.Columns[i].DataType.GetType();
        var colValue = dtFirst.Columns[i];
        flag = dtSecond.AsEnumerable().Any(T => typeof(T).GetProperty(colName).GetValue(T, typeof(colDataType)) == colValue);
    }
}