SELECT d1.*, s1.name AS name1, s2.name AS name2 FROM data_b d1 LEFT JOIN selo s1 ON id_selo1 = s1.id LEFT JOIN selo s2 ON id_selo2 = s2.id
SELECT selo1.name, selo2.name, data_b.commentar FROM data_b JOIN selo AS selo1 ON selo1.id = data_b.id_selo1 JOIN selo AS selo2 ON selo2.id = data_b.id_selo2