MySQL UNIÓN COMPLETA?

MySQL carece de soporte para FULL OUTER JOIN.

Entonces, si desea emular una unión completa en MySQL, eche un vistazo aquí .

Una solución comúnmente sugerida se ve así:

SELECT  t_13.value AS val13, t_17.value AS val17
FROM    t_13
LEFT JOIN
        t_17
ON      t_13.value = t_17.value
UNION ALL
SELECT  t_13.value AS val13, t_17.value AS val17
FROM    t_13
RIGHT JOIN
        t_17
ON      t_13.value = t_17.value
WHERE   t_13.value IS NULL
ORDER BY
        COALESCE(val13, val17)
LIMIT 30