devolver el mayor valor de una columna

[jurena]

Prueba esta, mancemo;

Código sql:

SELECT t1.numdoc, IFNULL( t4.serie, "" ) SERIE, IFNULL( t4.idres, "" ) IDRES
FROM tabla1 t1
LEFT JOIN (
 
SELECT t2.numdoc, t2.serie, t2.idres
FROM tabla2 t2
INNER JOIN (
 
SELECT numdoc num, MAX( idres ) maximo
FROM tabla2
GROUP BY numdoc
)t3 ON t2.numdoc = t3.num
AND t2.idres = t3.maximo
)t4 ON t1.numdoc = t4.numdoc
ORDER BY t1.numdoc