DataSet ds = new DataSet();
// 省略ds的Fill代码
DataTable products = ds.Tables["Product"];
IEnumerable<DataRow> rows = from p in products.AsEnumerable()select p;
foreach (DataRow row in rows)
{Console.WriteLine(row.Field<string>("ProductName"));
}

DataSet ds = new DataSet();
// 省略ds的Fill代码
DataTable products = ds.Tables["Product"];
var rows = products.AsEnumerable().Select(p => new{ProductID = p.Field<int>("ProductID"),ProductName = p.Field<string>("ProductName"),UnitPrice = p.Field<decimal>("UnitPrice")});
foreach (var row in rows)
{Console.WriteLine(row.ProductName);
}

var products = ds.Tables["Product"].AsEnumerable();
var query = from p in productsselect p.Field<string>("ProductName");

var rows = products.AsEnumerable().Where(p => p.Field<decimal>("UnitPrice") > 10m).Select(p => new{ProductID = p.Field<int>("ProductID"),ProductName = p.Field<string>("ProductName"),UnitPrice = p.Field<decimal>("UnitPrice")});

var rows = products.AsEnumerable().Where(p => p.Field<decimal>("UnitPrice") > 10m).OrderBy(p => p.Field<int>("SortOrder")).Select(p => new{ProductID = p.Field<int>("ProductID"),ProductName = p.Field<string>("ProductName"),UnitPrice = p.Field<decimal>("UnitPrice")});

var expr = from p in products.AsEnumerable()orderby p.Field<int>("SortOrder")select p;
IEnumerable<DataRow> rows = expr.ToArray();
foreach (var row in rows)
{Console.WriteLine(row.Field<string>("ProductName"));
}

var expr = from p in ds.Tables["Product"].AsEnumerable()orderby p.Field<int>("SortOrder"), p.Field<string>("ProductName") descendingselect p;

var query = from p in ds.Tables["Product"].AsEnumerable()from c in ds.Tables["Category"].AsEnumerable()where p.Field<int>("CategoryID") == c.Field<int>("CategoryID")&& p.Field<decimal>("UnitPrice") > 10mselect new{ProductID = p.Field<int>("ProductID"),ProductName = p.Field<string>("ProductName"),CategoryName = c.Field<string>("CategoryName")};

var query = from p in ds.Tables["Product"].AsEnumerable()group p by p.Field<int>("CategoryID") into gselect new{CategoryID = g.Key,Products = g};foreach (var item in query)
{Console.WriteLine(item.CategoryID);foreach (var p in item.Products){Console.WriteLine(p.Field<string>("ProductName"));}
}

var expr = from p in ds.Tables["Product"].AsEnumerable()group p by p.Field<int>("CategoryID") into gselect new{CategoryID = g.Key,ProductsCount = g.Count()};