corelibraries-devexpress-dot-dataaccess-dot-datafederation-2cda24a4.md
A collection of ISelectExpression objects that define columns in the SELECT statement.
Namespace : DevExpress.DataAccess.DataFederation
Assembly : DevExpress.DataAccess.v25.2.dll
NuGet Package : DevExpress.DataAccess
public class SelectExpressionCollection :
List<ISelectExpression>
Public Class SelectExpressionCollection
Inherits List(Of ISelectExpression)
The following members return SelectExpressionCollection objects:
The SelectNode.Expressions property provides access to the SelectExpressionCollection instance.
This code snippet demonstrates how to create a federated data source that uses a filter with a parameter.
Note
The complete sample project How to Create a Federated Data Source at Runtime is available in the DevExpress Examples repository.
using DevExpress.DataAccess.DataFederation;
// ...
FederationDataSource federation = new FederationDataSource();
Source source = new Source("excelSource", CreateExcelDataSource("SalesPerson.xlsx", "Data"));
var sourceNode = new SourceNode(source, "Orders");
var query = new SelectNode(sourceNode)
{
Alias = "excel",
Expressions = {
new SelectColumnExpression(sourceNode, "OrderID"),
new SelectColumnExpression(sourceNode, "OrderDate"),
new SelectColumnExpression(sourceNode, "Sales Person"),
new SelectColumnExpression(sourceNode, "ProductName"),
new SelectColumnExpression(sourceNode, "Extended Price")
},
FilterString = "[Orders.CategoryName] = ?cat",
};
federation.Queries.Add(query);
federation.Fill(new[] {
new DevExpress.DataAccess.Sql.QueryParameter("cat", typeof(string), "Seafood") });
Imports DevExpress.DataAccess.DataFederation
' ...
Dim federation As New FederationDataSource()
Dim source As New Source("excelSource", CreateExcelDataSource("SalesPerson.xlsx", "Data"))
Dim sourceNode = New SourceNode(source, "Orders")
Dim query = New SelectNode(sourceNode)
query.Alias = "excel"
query.Expressions.Add(New SelectColumnExpression(sourceNode, "OrderID"))
query.Expressions.Add(New SelectColumnExpression(sourceNode, "OrderDate"))
query.Expressions.Add(New SelectColumnExpression(sourceNode, "Sales Person"))
query.Expressions.Add(New SelectColumnExpression(sourceNode, "ProductName"))
query.Expressions.Add(New SelectColumnExpression(sourceNode, "Extended Price"))
query.FilterString = "[Orders.CategoryName] = ?cat"
federation.Queries.Add(query)
federation.Fill( {
New DevExpress.DataAccess.Sql.QueryParameter("cat", GetType(String), "Seafood") })
Object List<ISelectExpression> SelectExpressionCollection
See Also