均值与中位数
按行业计算《财富》500 强公司资产的均值（avg()）和中位数。
使用 percentile_disc() 函数计算中位数：
percentile_disc(0.5)
WITHIN GROUP (ORDER BY column_name)
本练习是课程的一部分
SQL 中的探索性数据分析
练习说明
- 选择
assets的均值和中位数。 - 按
sector分组。 - 按均值对结果排序。
交互式实操练习
通过完成这段示例代码来试试这个练习。
-- What groups are you computing statistics by?
SELECT ___,
-- Select the mean of assets with the avg function
___ AS mean,
-- Select the median
___(___) ___ ___ (___ ___ ___) AS median
FROM fortune500
-- Computing statistics for each what?
GROUP BY ___
-- Order results by a value of interest
ORDER BY ___;