/// <summary>
/// 以DataRelation實作DataTable中的Sum運算
/// </summary>
/// <param name="ds"></param>
private static void ComputeSum(DataSet ds)
{
DataTable orderDt = ds.Tables["OrderDetail"];
DataTable sumDt = new DataTable();
sumDt.TableName = "GruopSum";
sumDt.Columns.Add("ProductId", typeof(int));
sumDt.Columns.Add("Discount", typeof(decimal));
sumDt.Columns.Add("Sum", typeof(int));
//寫入group by的兩個欄位
foreach (DataRow dr in orderDt.Rows)
{
if (sumDt.Select(string.Format("productId = {0} and discount = {1}", dr["ProductId"], dr["Discount"])).Length == 0)
{
sumDt.Rows.Add(new object[] { dr["ProductId"], dr["Discount"] });
}
}
ds.Tables.Add(sumDt);
//指定group by欄位對應, 加入relation
ds.Relations.Add("GroupSumRelation",
new DataColumn[] { sumDt.Columns["ProductId"], sumDt.Columns["Discount"] },
new DataColumn[] { orderDt.Columns["ProductId"], orderDt.Columns["Discount"] });
//指定彙總函數運算使用的relation及欄位
sumDt.Columns["Sum"].Expression = "Sum(Child(GroupSumRelation).Quantity)";
PrintData.PrintDataSet(ds);
}
static void Main(string[] args)
{
DataSet ds;
//ds = GetDataByAdapter();
ds = GetDataByReader();
//資料來源須配合GetDataByAdapter()
//UpdateProductName(ds);
PrintData.PrintDataSet(ds);
//資料來源須配合GetDataByAdapter()
//BulkCopy(ds);
Console.ReadKey();
}