SELECT job,
CASE WHEN COUNT(job)%2=0 THEN TRUNCATE(COUNT(job)/2,0)
ELSE TRUNCATE(FLOOR(COUNT(job)/2)+1,0)
END start
,
CASE WHEN COUNT(job)%2=0 THEN TRUNCATE(COUNT(job)/2,0)+1
ELSE TRUNCATE(FLOOR(COUNT(job)/2)+1,0)
END end
FROM grade
GROUP BY job
ORDER BY job ASC