lo puse asi
"SELECT idalumno,count(idalumno)
FROM alumnos,programa, calificar
WHERE alumnos.idalumno=calificar.idalumno and
alumnos.programa=programa.idprograma
and calificar.promedio<programa.Minima
GROUP BY idalumno
HAVING count(idalumno)>3";
Pero me arroja lo sig
Column 'idalumno' in field list is ambiguous