CREATE OR REPLACE FUNCTION func()
LANGUAGE SQL AS $$

WITH sub AS (SELECT
...тут всякие агрегаты и CASE-ы...
)

-- а дальше пытаюсь генерить саму таблицу:
SELECT
concat('<tr>
<td>', name3, '</td>
<td>', total1, '</td>
<td>', total7, '</td>
<td>', total30, '</td>
<td>', total_week, '</td>
<td>', total_month, '</td>
<td>', total_q, '</td>\n',
(CASE WHEN active IS NOT NULL THEN '<td class=''bg15''>' || active || '</td>' ELSE '<td></td>' END), -- вставить класс
'\n</tr>'
) -- concat
FROM sub

UNION ALL
SELECT concat(
'<tr class=''total''>
<td>ИТОГО:</td>
<td>', sum(total1), '</td>
<td>', sum(total7), '</td>
<td>', sum(total30), '</td>
<td>', sum(total_week), '</td>
<td>', sum(total_month), '</td>
<td>', sum(total_q), '</td>
<td>', sum(total_active), '</td>
</tr>')
FROM sub;

$$;