Para que un pivot si se puede solucionar de esta manera:
Código SQL:
Ver originalSELECT SUM(total) AS Tareas_totales, SUM(entregadas) AS entregadas FROM
(
SELECT COUNT(*) AS tareas AS total, 0 AS entregadas FROM TAREA
UNION ALL
SELECT 0 AS total, COUNT(idTarea) AS entregadas FROM ENTREGAS WHERE idAlumno = 98
) t1
saludos!