DDzia

using System;
using System.Diagnostics;
using System.Linq;
using Microsoft.Owin;
using Owin;

[assembly: OwinStartup(typeof(WebApplication5.Startup))]

namespace WebApplication5
{

DDzia

var conn = new SqlConnection("some connection string");
var db = new DatabaseContext(conn);

const string tableName = "dbo.tUsers";
var dataFound = db.QueryToTable(tableName)
    .Where(x => (string)x["UserName"] == "Dzianis")
    .ToList();

DDzia

foreach (Row currentRow in rows)
{
    //write the row start element with the attributes added above 
    _writer.WriteStartElement(currentRow);

    foreach (OpenXmlElement currentCell in currentRow.ChildElements)
    {
        var cell = (Cell)currentCell;

        //write the start of the cell element with the type and cell reference attributes