Session.ExecuteQueryAsync(String, String[], Object[], CancellationToken) Method

Asynchronously executes the specified SQL query and returns a result set.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v24.2.dll

Declaration

C#

public Task<SelectedData> ExecuteQueryAsync(
    string sql,
    string[] parameterNames,
    object[] parameterValues,
    CancellationToken cancellationToken = default(CancellationToken)
)

VB.NET

Public Function ExecuteQueryAsync(
    sql As String,
    parameterNames As String(),
    parameterValues As Object(),
    cancellationToken As CancellationToken = Nothing
) As Task(Of SelectedData)

Parameters

Name	Type	Description
sql	String	Specifies an SQL statement.
parameterNames	String[]	Specifies parameter names.
parameterValues	Object[]	An array of objects specifying parameters to pass to the database server along with the query.

Optional Parameters

Name	Type	Default	Description
cancellationToken	CancellationToken	null	A CancellationToken object that delivers a cancellation notice to the running operation.

Returns

Type	Description
Task<SelectedData>	A Task<TResult> that returns a result set compatible with XPDataView.

Remarks

Use ExecuteQueryAsync to asynchronously query data stores for result sets. You can visualize result sets via the XPDataView. To learn how to access the resulting data, refer to How to: Access Data in SQL Query Results.

The example below demonstrates how to use this method. Here, session is the Session instance.

C#

using System.Threading;
using System.Threading.Tasks;
using DevExpress.Xpo;
using DevExpress.Xpo.DB;
// ...
CancellationTokenSource cts = new CancellationTokenSource();
SelectedData data = await GetEmployeesSimpleDataAsync(cts.Token);
// ...
public async Task<SelectedData> GetEmployeesSimpleDataAsync(CancellationToken cancellationToken) {
    const string queryString = 
        @"SELECT EmployeeID, (FirstName + ' ' + LastName) as Name, City, Country 
        FROM [Northwind].[dbo].[Employees] 
        WHERE City = @p1";
    return await session.ExecuteQueryAsync(queryString,
       new string[] { "p1" },
       new object[] { "London" },
       cancellationToken);
}

VB.NET

Imports System.Threading
Imports System.Threading.Tasks
Imports DevExpress.Xpo
Imports DevExpress.Xpo.DB
' ...
Private cts As New CancellationTokenSource()
Private data As SelectedData = Await GetEmployeesSimpleDataAsync(cts.Token)
' ...
Public Async Function GetEmployeesSimpleDataAsync(ByVal cancellationToken As CancellationToken) As Task(Of SelectedData)
    Const queryString As String = "SELECT EmployeeID, (FirstName + ' ' + LastName) as Name, City, Country 
        FROM [Northwind].[dbo].[Employees] 
        WHERE City = @p1"
    Return Await session.ExecuteQueryAsync(queryString, _
        New String() { "p1" }, New Object() { "London" }, cancellationToken)
End Function

Note that a format of parameter names in a SQL statement depends on the ADO.NET provider and database you use.

To learn more about executing SQL queries in XPO, refer to Direct SQL Queries.

Note

The ExecuteQueryAsync method sends queries directly, so the correct query syntax depends on a particular database server.