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Posted by Tony on 10/13/83 11:17
"Bob Stearns" <rstearns1241@charter.net> wrote in message
news:agTme.17634$cP2.440@fe06.lga...
> Mark & Ingrid Nugent wrote:
>> One table of my database could contain multiple values eg
>> student_courses, each student could have done many different courses.
>>
>> For a search engine, I want to be able to tick a checkbox and get all the
>> students who have done that course. However, if I tick two or more
>> checkboxes I want to get only the students that have done all the
>> selected courses, not the students that have done just any of the
>> selected courses.
>>
>> I think that means I will have to run a query "SELECT student_id FROM
>> student_courses WHERE course_id = $id OR course_id = $id etc etc , and
>> filter the results with PHP.
>> Has anyone got a neat solution? Is there any way that MySQL could refine
>> the query results?
>>
>> Mark
> SELECT student_id FROM student_courses WHERE course_id = $id1
> INTERSECT
> SELECT student_id FROM student_courses WHERE course_id = $id2
>
> should do what you want.
Umm - according to the MySQL website (
http://dev.mysql.com/doc/mysql/en/todo-sometime.html ), INTERSECT is not yet
supported - it's on the To-Do list. Is that information incorrect?
I'll have to give it a try on my server later :)
Mark:
As I understand it, you are going to have a list of checkboxes that may or
may not be checked, right? Let's say you have 3 checkboxes - if one is
checked, you want everyone who has taken that one course. If two are
checked, you want everyone who has taken BOTH courses, not one or the other,
right?
What is the actual database structure? Is it set so that you have a separate
entry for each course (i.e. a student who takes 3 courses would have 3 rows
entered in the database)?
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