Question

I have an SQL LIKE:

SELECT S.*, 
   (SELECT I.NAME FROM institution I, inst_map IM 
           WHERE IM.STUDENT = S.ID AND IM.INSTITUTION = I.ID) as INSTITUTIONS 
FROM student S

In this case it is possible for my subquery to return multiple records (I will get an error: Subquery returns more than 1 row).

How to show those multiple values from my subquery in one field (in my case INSTITUTIONS ) separated by commas?

All ideas are welcome.

Answer 1

Try this query –

SELECT s.*, GROUP_CONCAT(t.NAME) INSTITUTIONS FROM student s
  LEFT JOIN (SELECT * FROM institution i
              JOIN inst_map im
                ON im.INSTITUTION = i.ID
             ) t
  ON s.ID = t.STUDENT
GROUP BY s.ID

The GROUP_CONCAT function will help you to get values separated by commas.