Question

表：服务

id companyid jobid
 1         1     1
 2         1     2
 3         1     2
 4         2     3
 5         3     4
 6         3     1
 7         4     2
 8         5     2

我输入以下查询：

SELECT *
FROM service
WHERE jobID = 2
ORDER BY companyID desc, ID desc

我得到以下输出：

id companyid jobid
 8         5     2
 7         4     2
 3         1     2 
 2         1     2

但我希望我的预期输出如下：

id companyid jobid
 8         5     2
 7         4     2
 3         1     2

如何修改查询以获得预期的输出？

Answer 1

您应该只需应用max函数和group by子句：

select max(id) id, companyid, jobid
from service
where jobid = 2
group by companyid, jobid
order by id desc

根据您的样本数据，结果将是：

id  companyid   jobid
8   5           2
7   4           2
3   1           2

Answer 2

这应该有效：

select * from service s1
join (select max(id) as id 
      from service 
       group by jobid, companyid) s2 on s1.id = s2.id
where s1.jobid = 2--can comment to select all latest jobs

根据工作ID显示最新的ID和公司ID

2 个答案: