Table structure

[infomorelos]

HI,

I've been working on a little grade system but can't decide how I should organize the data. Somebody told me that I shouldn't care about data output when planning the database, instead I should concentrate on data requirements only. So I made 3 tables: 'pupils' (p_id,p_name), 'subjects' (s_id,s_name) and 'grades' (p_id, s_id, month_no, grade) and after some experimenting ond with a little help of my friends I got as far as the following output:

Charly (pupil's name)
----------Jan Feb Mar Apr May..............average
English-----8---9-----8------------9----------8.5
Maths------9---10---10-----10----------------9.5
Behaviour---8---8-----9------9-----9----------8.6

or

English
------------Jan Feb Mar.........average
Carmen------9----9----9-------- 9
Charly-------8----9---- 8-------- 8.5
Paul---------7----8----9---------8


I said 'Wow' all this without unique subject_month fields, especially Charly's missing grade for English / April. But now, I would like to get something like a monthly average for all subjects for a given pupil.
I wonder if this will be possible without the unique subject_month fields at the input side or if i must change my db structure.

PS:Unfortunately this forum doesn't respect white spacess and the tables are a little bit shifted, after three edits of this post I hopr you forgive me on that.

[kyberfabrikken]

PS:Unfortunately this forum doesn't respect white spacess and the tables are a little bit shifted, after three edits of this post I hopr you forgive me on that.

put it in a [code] block

[kyberfabrikken]

You should be looking at JOIN's
http://www.w3schools.com/sql/sql_join.asp

[infomorelos]

How do you think I could get the output examples without JOINS ? The real problem is to display the data having empty months column fields as shown in my output examples. That was not much of a help here. thanks for the [code]block tip.