javascript - how to set the content of a sql field using the Tinymce editor

one text

I want to get (set) the HTML content that is stored in the field called "Content" in SQL, to display it in PDF when the user presses the "print" button the PDF is generated I am using PHP, JS, the Fpdf library and the Tinymce editor

What the Tinymce documentation tells me to set implement this code: tinymce.get('my_editor').setContent(data); that code I apply it in the fpdf library but it doesn't recognize the tinymce code I have tried but I don't get results

This is my fpdf library code

 $q = "SELECT TB_Memo.ID_Memo, TB_Memo.Fecha_Creacion, a.Nombres +' '+ a.Apellidos as Destinatarios, b.Nombres + ' ' + b.Apellidos as Remitente, TB_Memo.Asunto, TB_Memo.Contenido, TB_Memo.ID_TipoMemo, TB_Memo.ID_EstadoMemo, TB_Memo.Fecha_Envio, a.ID_Empleado as IEM1, b.ID_Empleado as IEM2, TB_Memo.ID_Memorandum
    from TB_Memo
    inner join TB_Destinatario on TB_Memo.ID_Memo = TB_Destinatario.ID_Memo
    inner join TB_Remitente on TB_Memo.ID_Memo = TB_Remitente.ID_Memo
    inner join [IHTT_RRHH].[dbo].[TB_Empleados] a on TB_Destinatario.ID_Empleado = a.ID_Empleado
    inner join [IHTT_RRHH].[dbo].[TB_Empleados] b on TB_Remitente.ID_Empleado = b.ID_Empleado 
    WHERE TB_Memo.ID_Memo = :ID";
    $datos = select($q,array(':ID'=> $_GET['num'] ));
    $traerDatos = tinymce.get('mensaje').setContent($datos);

  $pdf->MultiCell(0,6,html_entity_decode($traerDatos, ENT_COMPAT),0,1) ;

JS code of the print function

function Imprimir(id) {
  $('#modalconsulta').modal('show'); 
 $("#divreporte").html('<div class="video-container">  <iframe width="100%" height="600" src="reporteMemo.php?num='+id+'" frameborder="0" allowfullscreen=""></iframe></div>');
}

HTML code where is the id tinymce

textarea id="mensaje" name="mensaje" required textarea