Session.ExecuteScalar(String, String[], Object[]) 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.v24.2.dll

Declaration

C#

public object ExecuteScalar(
    string sql,
    string[] parameterNames,
    object[] parameterValues
)

VB.NET

Public Function ExecuteScalar(
    sql As String,
    parameterNames As String(),
    parameterValues As Object()
) As Object

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.

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 GetEmployeeOrdersCount(int employeeId) {
    return (int)session.ExecuteScalar(
        "SELECT COUNT(*) FROM [Northwind].[dbo].[Orders] WHERE [EmployeeID] = @p1", 
        new string[] { "p1" }, 
        new object[] { employeeId }
    );        
}

VB.NET

Public Function GetEmployeeOrdersCount(ByVal employeeId As Integer) As Integer
    Return CInt(session.ExecuteScalar( _
        "SELECT COUNT(*) FROM [Northwind].[dbo].[Orders] WHERE [EmployeeID] = @p1", _
        New String() { "p1" }, _
        New Object() { employeeId }))
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 ExecuteScalar method sends queries directly, so the correct query syntax depends on a particular database server.