SELECT t.id AS "ID",
t.val AS "VALUE",
te.ext_val AS "EXT_VALUE",
t.val * 2.2 AS "RATED VALUE"
FROM table_main t
LEFT OUTER JOIN table_ext te ON t.id = te.id
AND te.ext_name = 'ADD_ATTR'
WHERE t.val > 0
AND t.id = 2