September 22nd, 2003, 06:38 PM
Question regarding SELECT
I have these two tables:
id | last_name
1 | Thomas
2 | Andrews
3 | Scott
(the student_id here is linked to the id from above).
student_id | grade
2 | E
1 | A
3 | B
4 | E
6 | F
Now, there isn't a student with id '6' from the student table, but is in the student_id.
I send over the following SQL statement:
"SELECT id, grade from grades where student_id=students.id ORDER BY students.last_name"
This is fine. It finds the students in both the grade table AND the students table and displays them in order by their last name.
However, what about for id '6', where they are not in the student table? If I do:
"SELECT id, grade from grades where student_id!=studentds_id"
This outputs ALL the student id's in the table.
Are there any other methods I could do this by? I just want a list of students not in the students table....
September 22nd, 2003, 11:50 PM
"a list of students not in the students table..."
select G.student_id, G.grade
from grades G
join students S
on G.student_id = S.id
where S.id is null
September 23rd, 2003, 12:00 AM
Thank you very much. I will have to read up on it to understand it more as I don't even know what a "Left outer join" is...