When I try to clean the result of my query and output it in console it returns "undefined" for both the value tag and the options content. I know I am using the correct column names for this. I am using the nodejs mssql package for this. Any idea on why this is happening and how to fix it?

querymodule

const query = () =>{
    var output =``
    sql.connect(config).then(pool => {
        // Query
        
        return pool.request()
            .query('SELECT Pdf_Filename, SKU FROM RDCProductLabels WHERE PDF_Filename is not null Order by SKU')
    }).then(result => {
        for(data in result){
            output +=`
                        <option value="${data.PDF_Filename}">
                            ${data.SKU}
                        </option>
                     `
        }

        console.log(output)
        
    }).catch(err => {
       console.log(`an error occurred - ${err}`)
    });
}

generated html

  <option value="undefined">
      undefined
  </option>

  <option value="undefined">
      undefined
  </option>

  <option value="undefined">
      undefined
  </option>

  <option value="undefined">
      undefined
  </option>

  <option value="undefined">
      undefined
  </option>