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")) / 10000, 2));