我无法一起使用JOINS和group-by: 我搜索了这个......但我找不到解决方案..问题如下:
我有两个表,第一个是main_table
,其中包含字段eid
,name
,status
第二个表是对字段fid
,eid
,last_date
,remarks
和next_date
第二个表用于存储客户端的后续详细信息(存储在main_table中的客户端详细信息),我希望获得具有所选日期周期(from_date到to_date)的每个客户端的最后一个后续记录,并按降序排序next_date。
我使用了以下查询但没有工作
SELECT *
FROM main_table as MT
JOIN followups as MF on MT.eid=MF.eid
WHERE MT.status='open' AND MF.NDate<='2012-12-07'
GROUP BY MF.eid
ORDER BY MF.next_date DESC
提前感谢......伙计们
答案 0 :(得分:2)
您可以尝试这样的事情:
select m.eid,
m.name,
m.status,
f1.last_date,
f1.remarks,
f1.next_date
from maintable m
left join
(
select max(last_date) maxLast, eid
from followups
where last_date between from_date and to_date
group by eid
) f
on m.eid = f.eid
left join followups f1
on f.maxLast = f1.last_date
and f.eid = f1.eid
where m.status='open'
and f1.next_date<='2012-12-07'
order by f1.next_date desc
答案 1 :(得分:1)
试试这个:
SELECT * FROM main_table AS MT
LEFT JOIN (SELECT * FROM (SELECT * FROM followups WHERE NDate<='2012-12-07' ORDER BY next_date DESC) AS A GROUP BY eid) AS MF ON MT.eid=MF.eid
WHERE MT.status='open';
答案 2 :(得分:1)
试试这个
SELECT * FROM main_table AS MT
LEFT JOIN (SELECT * FROM (SELECT * FROM followups ORDER BY next_date DESC) AS A GROUP BY eid) AS MF ON MT.eid=MF.eid
WHERE MT.status='open'
AND MF.NDate<='2012-12-07';