psql (11.2 (Debian 11.2-1.pgdg90+1))
Введите "help", чтобы получить справку.

gasu=> SELECT xmlelement(name row, xmlattributes(test)) from  (select 'Привет' as test) tt
;
                        xmlelement
----------------------------------------------------------
 <row test="&#x41F;&#x440;&#x438;&#x432;&#x435;&#x442;"/>
(1 строка)

gasu=> SELECT query_to_xml($$ select 'Привет' as test $$, true, true, '');
                        query_to_xml
-------------------------------------------------------------
 <row xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">+
   <test>Привет</test>                                      +
 </row>                                                     +
                                                            +

(1 строка)

gasu=>