// var products = [{ sku: 1 }, { sku: 2 }]; // Sample data (SKU of products from Magento Database)

var productsSku = products
  .map(product => product.sku.toString())
  .map(sku => sku.split(' ').filter(node => node.match(/^\S+$/)))
  .reduce((acc, target) => Array.prototype.concat.apply(acc, target))
  .filter((value, index, self) => self.indexOf(value) === index)
  .map(sku => `'${sku}'`)
  .sort((x, y) => x - y)
  .join(', ');

console.log(`SELECT Codigo, Descricao, DataCad, PrecoCusto FROM Alpha3.dbo.Produtos WHERE Codigo NOT IN (${productsSku})`);