fix mysql build student report

test plan
 - specs should pass

Change-Id: Ibf7d19287de12f5802a200485951e92c62694f68
Reviewed-on: https://gerrit.instructure.com/29602
Tested-by: Jenkins <jenkins@instructure.com>
Reviewed-by: Cody Cutrer <cody@instructure.com>
Product-Review: Rob Orton <rob@instructure.com>
QA-Review: Rob Orton <rob@instructure.com>