Compute和Linq的Field使用

目录：

• Compute的使用
• Field的使用

1.Compute

案例：

 private void ComputeBySalesSalesID(DataSet dataSet)
 {
     // Presumes a DataTable named "Orders" that has a column named "Total."
     DataTable table;
     table = dataSet.Tables["Orders"];
 
     // Declare an object variable.
     object sumObject;
     sumObject = table.Compute("Sum(Total)", "EmpID = 5");
 }

  DataTable dt = null;
 dt=...
 decimal money = Convert.ToDecimal(dt.Compute("Sum(money)", "true"));

2.Field的使用(根据dt获取每个列的数据)

案例：

 // Fill the DataSet.
 DataSet ds = new DataSet();
 ds.Locale = CultureInfo.InvariantCulture;
 FillDataSet(ds);
 
 DataTable products = ds.Tables["Product"];
 
 var query =
     from product in products.AsEnumerable()
     where product.Field<string>("Color") == "Red"
     select new
     {
         Name = product.Field<string>("Name"),
         ProductNumber = product.Field<string>("ProductNumber"),
         ListPrice = product.Field<Decimal>("ListPrice")
     };
 
 foreach (var product in query)
 {
     Console.WriteLine("Name: {0}", product.Name);
     Console.WriteLine("Product number: {0}", product.ProductNumber);
     Console.WriteLine("List price: ${0}", product.ListPrice);
     Console.WriteLine("");
 }

结合linq语句

 decimal money = dt.AsEnumerable().Sum(t => Math.Round((t.Field<Decimal>("money")) / , ));