moodle get feedback item

when i try get the feedback items, i receipt only the first column, why? ``` SELECT u.firstname as "Usuario", CASE WHEN i.name = 'task 1' THEN v.value END AS "1", CASE WHEN i.name = 'task 2' THEN v.value END AS "2", CASE WHEN i.name = 'task 3' THEN v.value END AS "3", CASE WHEN i.name = 'task 4' THEN v.value END AS "4", CASE WHEN i.name = 'task 5' THEN v.value END AS "5", CASE WHEN i.name = 'task 6' THEN v.value END AS "6", CASE WHEN i.name = 'task 7' THEN v.value END AS "7", CASE WHEN i.name = 'task 8' THEN v.value END AS "8", CASE WHEN i.name = 'task 9' THEN v.value END AS "9", CASE WHEN i.name = 'task 10' THEN v.value END AS "10", CASE WHEN i.name = 'task 11' THEN v.value END AS "11", CASE WHEN i.name = 'task 12' THEN v.value END AS "12" FROM prefix_feedback AS f JOIN prefix_course AS c ON c.id=f.course JOIN prefix_feedback_item AS i ON f.id=i.feedback JOIN prefix_feedback_completed AS fc ON f.id=fc.feedback LEFT JOIN prefix_feedback_value AS v ON v.completed=fc.id AND v.item=i.id JOIN prefix_user AS u ON fc.userid=u.id GROUP BY u.firstname ORDER BY u.id, i.id, i.name ``` and when i remove the group by i get all columns but on a lot of rows [capture][1] [1]: https://i.sstatic.net/u1Fuj.jpg