簡單的連表統計某個ID出現的次數則sql類似：
select t2.*,( select count(t1.id) from cook_comment t1 where t1.goodsId=t2.id ) as commentNumber from goods t2 ;
涉及到多列需要作爲查詢分組的如下示例：sql聯表查詢根據共同字段group by分組統計數據並顯示，
行數據：
select a.*, t.starttime, t.endtime
from (select l.jobid,
l.kddate,
sum(l.count) updateTimes,
sum(decode(l.status, 2, 1, 0)) failTimes,
sum(l.cost) totalCost,
sum(l.rowsize) updateSize
from kdgs_realtime_log l
-- where l.kddate = 20171017
-- and l.jobId = 1000009
--and l.status = 2
group by l.jobid, l.kddate) a,
kdgs_qrtz_trigger_info t
where t.id = a.jobid
如果只需要查詢某條ID對應的數據則需要把相關where註釋打開。
彙總信息低效率的方式是不用group by而是逐一查詢各數據再展示，如下
select * from kdgs_realtime_log t where t.jobid = 1000009;
select i.id,i.starttime,i.endtime,
(select sum(l.count) from kdgs_realtime_log l where l.jobid=i.id and l.kddate=20171018) as updateTimes,
(select count(1) from kdgs_realtime_log l where l.jobid=i.id and l.kddate=20171018 and l.status=2) as failTimes,
(select sum(l.cost) from kdgs_realtime_log l where l.jobid=i.id and l.kddate=20171018) as totalCost,
(select sum(l.rowsize) from kdgs_realtime_log l where l.jobid=i.id and l.kddate=20171018) as updateSize
from kdgs_qrtz_trigger_info i where i.id=1000009;