mysql跑99分位、80分位、中位数的方法

# 分两步得到 第一步 假设得到的值为1000000
SELECT FLOOR(COUNT(*) * 0.99) FROM (select count(*) as cnt from mytablename group by uid) tmpb;
# 获取的第一个值即为99分位的数据
SELECT cnt FROM (select uid,count(*) as cnt from mytablename group by uid) tmpa ORDER BY cnt ASC LIMIT 1000000, 1;