php - 给定 MySQL 的返回数量，如何找到平均 AGI？

Question

数据可从 IRS 免费获得 2008 年按邮政编码划分的收入数据。

A00100 是调整后的总收​​入(又名 AGI)，agi_class 是调整后的总收​​入的大小。范围从 1 到 7:

1 = 'Under $10,000'
2 = '$10,000 under $25,000'
3 = '$25,000 under $50,000'
4 = '$50,000 under $75,000'
5 = '$75,000 under $100,000'
6 = '$100,000 under $200,000'
7 = '$200,000 or more '

“退税数量”是该 agi_class 的纳税申报数量。

mysql> select A00100,zipcode,agi_class,N1 as 'Number of Returns' from taxbyzip2008 where     zipcode="10021";
+-------------+---------+-----------+-------------------+
| A00100      | zipcode | agi_class | Number of Returns |
+-------------+---------+-----------+-------------------+
|     -954234 | 10021   |         1 |              3589 |
|    43243455 | 10021   |         2 |              2521 |
|   149940475 | 10021   |         3 |              3939 |
|   243853640 | 10021   |         4 |              3936 |
|   262995399 | 10021   |         5 |              3025 |
|   751195421 | 10021   |         6 |              5333 |
| 10677437299 | 10021   |         7 |              7477 |
+-------------+---------+-----------+-------------------+

我需要为每个邮政编码计算平均 调整后总收入。我怎样才能在 MySQL 中做到这一点？谢谢!

Answer 1

select zipcode, 
       avg(A00100) as average_income
from taxbyzip2008 
group by zipcode