Jeg tror ikke, at MySQL understøtter UNDTAGET syntaks. Prøv at bruge NOT IN
eller en LEFT JOIN
:
SELECT s.sno
FROM students s
WHERE s.sno NOT IN
(
SELECT t.sno
FROM take t
WHERE t.cno = 'CS112'
);
ELLER
SELECT s.sno
FROM students s
LEFT JOIN take t ON s.sno = t.sno
WHERE IFNULL(t.cno, '') != 'CS112'
OPDATERING
Jeg hånede dine data som sådan, og de returnerer korrekt 5 til 10:
create temporary table temp_students (sno int)
insert into temp_students values (1)
insert into temp_students values (2)
insert into temp_students values (3)
insert into temp_students values (4)
insert into temp_students values (5)
insert into temp_students values (6)
insert into temp_students values (7)
insert into temp_students values (8)
insert into temp_students values (9)
insert into temp_students values (10)
create temporary table temp_take (sno int, cno varchar(50))
insert into temp_take values (1, 'CS112')
insert into temp_take values (2, 'CS112')
insert into temp_take values (3, 'CS112')
insert into temp_take values (4, 'CS112')
SELECT s.sno
FROM temp_students s
LEFT JOIN temp_take t ON s.sno = t.sno
WHERE IFNULL(t.cno, '') != 'CS112'