--- 1
SELECT
	ps.Pupil,
	pt.Target
FROM
	PupilStudying ps
	LEFT JOIN PupilTargets pt ON pt.pupil = ps.pupil
WHERE
	ps.Subject = 'Maths';

--- 2
SELECT
	ps.Pupil,
	pt.Target
FROM
	PupilStudying ps
	LEFT JOIN SubjectList sl ON sl.Subject = ps.Subject 
	LEFT JOIN PupilTargets pt ON pt.pupil = ps.pupil AND pt.TargetType = slTargetType
WHERE
	ps.Subject = 'Maths';

FROM
((PupilsStudying PS 
  INNER JOIN SubjectList SL ON PS.subject=SL.subject)
  LEFT JOIN PupilsTargets PT ON PT.pupil=PS.pupil AND PT.targettype=SL.targettype)