Question

I am trying to pull data using an mysql query that requires that I look for keywords within a field in the database.

A user in my database may have the following in their ‘subjects’ field:

‘math | science | reading | writing’

This means that user accepts all of those subjects. This table is called ‘user_teacher’

I have another table for students (called ‘student_requests’) that consists of requests from students for say, science, or math, or maybe even two subjects (so the entry in this case would look like ‘science | math’). This table stores those values also in a field called ‘subjects’.

My question is, how would I form a query where i am looking up entries in ‘student_requests’ where the subject matches any of the listed subjects within a particular user’s profile from the table ‘user_teacher’? Let’s assume that i originally look up the teacher’s subject field using something like this:

$query = "SELECT * FROM user_teacher WHERE username = '$username' LIMIT 1 ";
$result = mysql_query($query);
while ($row = mysql_fetch_object($result)) {
    $teacher_subjects=$row->subject;
}

In other words, if i am a teacher who offers reading and math, i want to see all entries in the ‘student_requests’ table where the subject field has ‘math’ or ‘reading’ in it.

Any assistance on this would be greatly appreciated. Also, if you think I am approaching this problem incorrectly based on how i have set up the tables, please let me know. My goal here is to have the queries run as quickly as possible.

Thanks!

Answer 1

You could try not using that kind of construction for you tables, instead make another table subjects (id, name) and other two tables students_requests (id, id_student, id_subject) [here you can record multiple requests for one student], and teach_subjects (id, id_teach, suject_id) [the same, multiple subject for a teacher] and yhen you can make a join, or even a plain php check between tables, based on what you received.

EDIT 1:

SELECT * FROM `students` WHERE `id` IN (SELECT `subject_id` FROM `students_request` INTERSECT SELECT `subject_id` FROM `teach_subject`);

And please change id_subject from students_requests in subject_id.