using IronXL;
using System.Data;
using System.Data.SqlClient;

//  Su consulta sql
string sql = "SELECT * FROM Users";

//  Su cadena de conexión
string connectionString = @"Data Source=.\SQLEXPRESS;Initial Catalog=usersdb;Integrated Security=True";

using (SqlConnection connection = new SqlConnection(connectionString))
{
    //  Conexiones abiertas a la base de datos
    connection.Open();
    SqlDataAdapter adapter = new SqlDataAdapter(sql, connection);
    DataSet ds = new DataSet();
    //  Rellenar DataSet con datos
    adapter.Fill(ds);

    //  Crear un libro de Excel a partir del DataSet SQL
    WorkBook workBook = WorkBook.Load(ds);
}

Imports IronXL
Imports System.Data
Imports System.Data.SqlClient

'  Su consulta sql
Private sql As String = "SELECT * FROM Users"

'  Su cadena de conexión
Private connectionString As String = "Data Source=.\SQLEXPRESS;Initial Catalog=usersdb;Integrated Security=True"

Using connection As New SqlConnection(connectionString)
	'  Conexiones abiertas a la base de datos
	connection.Open()
	Dim adapter As New SqlDataAdapter(sql, connection)
	Dim ds As New DataSet()
	'  Rellenar DataSet con datos
	adapter.Fill(ds)

	'  Crear un libro de Excel a partir del DataSet SQL
	Dim workBook As WorkBook = WorkBook.Load(ds)
End Using