SELECT student.stud_name, progress.mark FROM student INNER JOIN progress ON student.id_stud= progress.id_stud

SELECT AVG(mark) FROM progress GROUP BY id_stud

SELECT stud_name FROM student WHERE stip IN (1200, 1300, 1500)

SELECT id_subj, mark FROM progress WHERE mark > (SELECT AVG(mark) FROM progress)

SELECT student.stud_name, progress.mark FROM student, progress WHERE student.id_stud= progress.id_stud