先考虑奇偶性

考试分数(四)

http://www.nowcoder.com/questionTerminal/502fb6e2b1ad4e56aa2e0dd90c6edf3c

SELECT job, CASE WHEN count(id)%2=1 THEN (count(id)+1)/2
WHEN count(id)%2=0 THEN count(id)/2
END AS start,
CASE WHEN count(id)%2=1 THEN (count(id)+1)/2
WHEN count(id)%2=0 THEN (count(id)+2)/2
END AS END
FROM grade
GROUP BY job
ORDER BY job

依照题意有如下中位数区间
START END
奇数 (N+1)/2 (N+1)/2
偶数 N/2 (N+2)/2

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