Ejercicio VII Práctica GD

SELECT AVG(t1.importe_comision) AS promedio_comisiones, t3.razon_social,t3.cuit FROM comisiones AS t1 INNER JOIN contratos AS t2 ON t1.nro_contrato = t2.nro_contrato INNER JOIN empresas AS t3 ON t2.cuit = t3.cuit GROUP BY t2.cuit HAVING promedio_comisiones = MAX(promedio_comisiones) OR promedio_comisiones = MIN(promedio_comisiones)