How do I combine the results of two queries with ordering?

Question

How do you join the results of 2 queries, ordering by date?

SELECT * FROM table1 WHERE tag=\'1\'
SELECT * FROM table2 WHERE tag=\'3\'

table

Answer 1

SELECT * 
FROM   (SELECT * 
        FROM   table1 
        UNION 
        SELECT * 
        FROM   table2) t 
ORDER  BY t.DATE