SQL query of multiple values in one cell

Question

There is a table(Course Interests) which has all the values in one cell. But those values are just ids and I want to join them with another table(Course) so I can know their

Answer 1

Use FIND_IN_SET to search for something in a comma-delimited list.

SELECT i.MemberID, i.MemberName, GROUP_CONCAT(c.Course) AS CoursesInterested
FROM CourseInterests AS i
JOIN Course AS c ON FIND_IN_SET(c.CourseId, i.CoursesInterested)

However, it would be better to create a relation table instead of storing the courses in a single column. This type of join cannot be optimized using an index, so it will be expensive for a large table.