DataView 公开一个可枚举的 DataRowView 对象集合。 DataRowView 表示 DataRow 的一个自定义视图，并在控件中显示该 DataRow 的特定版本。 只有一个版本的 DataRow 可以通过控件显示，例如 DataGridView。 您可以通过 DataRow 的 DataRowView 属性访问 Row 公开的 DataRowView。 当使用 DataRowView 查看值时，RowStateFilter 属性决定公开基础 DataRow 的哪个行版本。 有关使用 a DataRow访问不同行版本的信息，请参阅 行状态和行版本。 因为 DataView 公开的 DataRowView 对象集合是可枚举的，所以你可以使用 LINQ to DataSet 对它执行查询。
以下示例查询 Product 表以获取红色产品，并从该查询创建表。 从表创建 A DataView ，属性 RowStateFilter 设置为筛选已删除和修改的行。 然后，它将 DataView 用作 LINQ 查询中的源，并且 DataRowView 已修改和删除的对象将绑定到控件 DataGridView 。
DataTable products = _dataSet.Tables["Product"];
// Query for red colored products.
EnumerableRowCollection<DataRow> redProductsQuery =
from product in products.AsEnumerable()
where product.Field<string>("Color") == "Red"
orderby product.Field<decimal>("ListPrice")
select product;
// Create a table and view from the query.
DataTable redProducts = redProductsQuery.CopyToDataTable();
var view = new DataView(redProducts);
// Mark a row as deleted.
redProducts.Rows[0].Delete();
// Modify product price.
redProducts.Rows[1]["ListPrice"] = 20.00;
redProducts.Rows[2]["ListPrice"] = 30.00;
view.RowStateFilter = DataViewRowState.ModifiedCurrent | DataViewRowState.Deleted;
// Query for the modified and deleted rows.
IEnumerable<DataRowView> modifiedDeletedQuery = from DataRowView rowView in view
select rowView;
dataGridView2.DataSource = modifiedDeletedQuery.ToList();
Dim products As DataTable = dataSet.Tables("Product")
' Query for red colored products.
Dim redProductsQuery = _
From product In products.AsEnumerable() _
Where product.Field(Of String)("Color") = "Red" _
Order By product.Field(Of Decimal)("ListPrice") _
Select product
' Create a table and view from the query.
Dim redProducts As DataTable = redProductsQuery.CopyToDataTable()
Dim view As DataView = New DataView(redProducts)
' Mark a row as deleted.
redProducts.Rows(0).Delete()
' Modify product price.
redProducts.Rows(1)("ListPrice") = 20.0
redProducts.Rows(2)("ListPrice") = 30.0
view.RowStateFilter = DataViewRowState.ModifiedCurrent Or DataViewRowState.Deleted
' Query for the modified and deleted rows.
Dim modifiedDeletedQuery = From rowView As DataRowView In view _
Select rowView
dataGridView2.DataSource = modifiedDeletedQuery.ToList()
以下示例从绑定到 DataGridView 控件的视图中创建产品表。 DataView 被用于查询红色产品，查询后的有序结果绑定在控件 DataGridView 上。
// Create a table from the bound view representing a query of
// available products.
var view = (DataView)bindingSource1.DataSource;
DataTable productsTable = view.Table;
// Set RowStateFilter to display the current rows.
view.RowStateFilter = DataViewRowState.CurrentRows;
// Query the DataView for red colored products ordered by list price.
var productQuery = from DataRowView rowView in view
where rowView.Row.Field<string>("Color") == "Red"
orderby rowView.Row.Field<decimal>("ListPrice")
select new
{
Name = rowView.Row.Field<string>("Name"),
Color = rowView.Row.Field<string>("Color"),
Price = rowView.Row.Field<decimal>("ListPrice")
};
// Bind the query results to another DataGridView.
dataGridView2.DataSource = productQuery.ToList();
' Create a table from the bound view representing a query of
' available products.
Dim view As DataView = CType(bindingSource1.DataSource, DataView)
Dim productsTable As DataTable = CType(view.Table, DataTable)
' Set RowStateFilter to display the current rows.
view.RowStateFilter = DataViewRowState.CurrentRows
' Query the DataView for red colored products ordered by list price.
Dim productQuery = From rowView As DataRowView In view _
Where rowView.Row.Field(Of String)("Color") = "Red" _
Order By rowView.Row.Field(Of Decimal)("ListPrice") _
Select New With {.Name = rowView.Row.Field(Of String)("Name"), _
.Color = rowView.Row.Field(Of String)("Color"), _
.Price = rowView.Row.Field(Of Decimal)("ListPrice")}
' Bind the query results to another DataGridView.
dataGridView2.DataSource = productQuery.ToList()