Session.ExecuteScalar(String) Method

Executes the specified SQL query and returns the first column of the first row in the result set returned by the query.

Namespace: DevExpress.Xpo

Assembly: DevExpress.Xpo.v19.1.dll

Declaration

C#

public object ExecuteScalar(
    string sql
)

VB.NET

Public Function ExecuteScalar(
    sql As String
) As Object

Parameters

Name	Type	Description
sql	String	A String value that specifies an SQL query.

Returns

Type	Description
Object	The first column of the first row in the query’s result set. If the column is not found in the result set, a null reference (Nothing in Visual Basic) is returned. If the value in the database is null, DBNull.Value is returned.

Remarks

Use ExecuteScalar to query data stores for a single or aggregate value, without having to retrieve a result set.

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

C#

public int GetOrdersCount() {
    return (int)session.ExecuteScalar(
        "SELECT COUNT(*) FROM [Northwind].[dbo].[Orders]"
    );        
}

VB.NET

Public Function GetOrdersCount() As Integer
    Return CInt(session.ExecuteScalar( _
        "SELECT COUNT(*) FROM [Northwind].[dbo].[Orders]"))
End Function

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

Note

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

Related GitHub Examples

The following code snippet (auto-collected from DevExpress Examples) contains a reference to the ExecuteScalar(String) method.

Note

The algorithm used to collect these code examples remains a work in progress. Accordingly, the links and snippets below may produce inaccurate results. If you encounter an issue with code examples below, please use the feedback form on this page to report the issue.

C#

XAF_server-side-timestamping-in-the-audit-trail-system-e1808/CS/AuditDemo.Module/MSSqlServerTimestampStrategy.cs#L13

public void OnBeginSaveTransaction(Session session) {
    cachedTimeStamp = (DateTime)session.ExecuteScalar("select getdate()");
}

VB.NET

XAF_server-side-timestamping-in-the-audit-trail-system-e1808/VB/AuditDemo.Module/MSSqlServerTimestampStrategy.vb#L17

Implements IAuditTimestampStrategy.OnBeginSaveTransaction
    cachedTimeStamp = CDate(session.ExecuteScalar("select getdate()"))
End Sub