public static T Sum <T>(this DataTable dt, string columName)
{
object result = DBNull.Value;
OperationWorker pw = new OperationWorker();
foreach (DataRow row in dt.Select())
{
result = pw.Plus(result, row[columName]);
}
return((T)result);
}
/// <summary>
/// group by specific Colunm, to sum up others Column value which is type of int/double/decimal etc.
/// </summary>
/// <param name="sourceTable"></param>
/// <param name="columnName"></param>
/// <returns></returns>
public static DataTable GroupBy(this DataTable sourceTable, string columnName)
{
DataTable midTable = sourceTable.Copy();
string marker = $"Column_{Guid.NewGuid().ToString("N")}";
string removeMarker = Guid.NewGuid().ToString("N");
midTable.Columns.Add(marker);
int colIndex = midTable.Columns.IndexOf(columnName);
foreach (var raw_row in midTable.Select())
{
DataRow[] resultRows = midTable.Select($"{columnName}='{raw_row[columnName]}' and {marker} is null");//
if (resultRows.Length < 1)
{
continue;
}
DataRow targetRow = midTable.Rows.Add();
foreach (var row in resultRows)
{
for (int i = 0; i < row.ItemArray.Length; i++)
{
object item = row.ItemArray[i];
if (colIndex == i)
{
targetRow[i] = item;
continue;
}
OperationWorker pw = new OperationWorker()
{
DbNullAction = (x, y) => { x = y; return(x); }
};
targetRow[i] = pw.Plus(targetRow[i], item);
}
row[marker] = removeMarker;
}
targetRow[marker] = marker;
}
foreach (var row in midTable.Select($"{marker}='{removeMarker}'"))
{
midTable.Rows.Remove(row);
}
midTable.Columns.Remove(marker);
return(midTable);
}
public static DataRow Max(this DataTable dt, string columnName)
{
int rowCount = dt.Rows.Count;
DataRow row = dt.FirstOrDefault();
if (row == null)
{
return(row);
}
OperationWorker pw = new OperationWorker();
for (int i = 1; i < rowCount; i++)
{
if (pw.LeftLarger(dt.Rows[i][columnName], row[columnName]))
{
row = dt.Rows[i];
}
}
return(row);
}