static public boolean validateEmail(String email){
        if(email == null || email.isEmpty()) return false;
        boolean resultado = false;
        try {
            db = DatabaseInstance.getInstance();
            ResultSet result;
            String squery = SQLHelper.generateSelect(DataContract.UsuarioEntry.TABLE_NAME, null);
            squery += SQLHelper.generateWhere(DataContract.UsuarioEntry.COLUMN_EMAIL, SQLHelper.WHERE_TYPE_EQUAL);
            PreparedStatement query = db.prepareStatement(squery);
            query.setString(1, email.toLowerCase());
            System.out.println(query);
            result = query.executeQuery();
            if(!result.first()){
                resultado = true;
                LOGGER.log(Level.WARNING, "Email no esta usado. {0}", resultado);
            }else{
                LOGGER.log(Level.WARNING, "Valid: {0}", result.toString());
            }
            
          
        } catch (SQLException ex) {
            LOGGER.log(Level.SEVERE,"Cannot get user data. Full error: "+ex.toString(),ex);
        }
            return resultado;
    }