I’m trying to display all my exercises which are in course A (course_id ‘1’)
When I run this query:
SELECT * FROM exercises LEFT JOIN sessions on sessions.session_id WHERE course_id ='1'
I get this:
It’s worth noting that courses have sessions and in that session there are these exercises. Realistically only exercise_id’s 1 and 4 are linked to course 1. So why are their duplicate rows being returned? Session_id’s 10, 11, 12 and 13 are all part of course 1 but do not have any exercises in them at present. Any help would be appreciated.
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Answer
Your in condition of the join is missing the condition.
Try something like
SELECT * FROM exercises LEFT JOIN sessions on exercises.session_id = sessions.session_id WHERE course_id ='1'
.