MySQL group by select聚合和一条特定记录同时

Question

此表已按 EMPLOYER-NAME、JOB_TITLE、WORKSITE_CITY、WORKSITE_STATE 和 IN_YEAR 分组，计算得出 AVG_ANNUAL_SALARY。

我想在下一个查询中做的是：

select EMPLOYER-NAME, JOB_TITLE, WORKSITE_CITY, WORKSITE_STATE,
    AVG(AVG_ANNUAL_SALARY) AS ANNUAL_SALARY,
    "Most recent year(could be 2015 or 2014 or 2013 or 2012)'s salary"
from table
group by EMPLOYER-NAME, JOB_TITLE, WORKSITE_CITY, WORKSITE_STATE

我是 mysql 新手，有人可以帮我检索双引号中的部分吗？ 谢谢！

Answer 1

试试这个查询：

select t1.EMPLOYER-NAME, t1.JOB_TITLE, t1.WORKSITE_CITY, t1.WORKSITE_STATE,
    AVG(t1.AVG_ANNUAL_SALARY) AS ANNUAL_SALARY, t2.AVG_ANNUAL_SALARY AS MOST_RECENT_SALARY
from table t1
group by EMPLOYER-NAME, JOB_TITLE, WORKSITE_CITY, WORKSITE_STATE
inner join
(
    select EMPLOYER-NAME, JOB_TITLE, WORKSITE_CITY, WORKSITE_STATE, AVG_ANNUAL_SALARY
    from table r1
    where r1.IN_YEAR = (
        select max(r2.IN_YEAR) from table r2
        where r1.EMPLOYER-NAME = r2.EMPLOYER-NAME and r1.JOB_TITLE = r2.JOB_TITLE
            and r1.WORKSITE_CITY = r2.WORKSITE_CITY
            and r1.WORKSITE_STATE = r2.WORKSITE_STATE
    )
) t2
ON t1.EMPLOYER-NAME = t2.EMPLOYER-NAME and t1.JOB_TITLE = t2.JOB_TITLE
    and t1.WORKSITE_CITY = t2.WORKSITE_CITY and t1.WORKSITE_STATE = t2.WORKSITE_STATE

说明：

内部查询为每个组查找最近一年的平均年薪。然后通过EMPLOYER-NAME、JOB-TITLE、WORKSITE_CITY 和WORKSITE_STATE 的组合将此临时表连接到原始查询中的表。

注意：

您可能可以通过假设 MySQL 默认只返回 GROUP BY 的第一行来摆脱一个大大简化的查询。 q.v. this SO post。但我会回避在生产中这样做，因为你永远不知道何时何地它可能不受支持。