Question

我的sqlite数据库中有两个表 - 招标和批量。

标段：

id
name
address

批次：

id
tender_id # it's tender's ID from table `tenders`
summ

一次招标可能有很多。如何计算有0手的投标？

我尝试了以下查询：

select lots.* from lots
inner join tenders on tenders.id = lots.tender_id
group by lots.id
having count(*) =0

和

SELECT COUNT(tenders.id) AS cnt FROM tenders, lots WHERE lots.tender_id = tenders.id group by tenders.id having cnt=0

没有结果。但是当我尝试做的时候

select * from lots where tender_id=263128

结果我看到0行。

谢谢。

Answer 1

SELECT tenders.id 
FROM tenders 
WHERE tenders.id NOT IN (SELECT tender_id FROM lots)

或不同数量的批次：

SELECT tenders.id
FROM tenders
WHERE tenders.id IN 
(
SELECT tender_id FROM lots GROUP BY tender_id HAVING COUNT(*) IN (2,3)
)

Answer 2

你的加入尝试看起来很有希望，但当然你没有得到任何结果，因为你选择了很多。

我会反过来做它left join，这样你可以检查批量null

select
        tenders.id
    from tenders
    left join lots on tenders.id = lots.tender_id
    where lots.tender_id is null

或者，如果您想检查每次招标的具体抽签次数：

select
        tenders.id
    from tenders
    left join lots on tenders.id = lots.tender_id
    group by tenders.id
    having count(*) = 2

Answer 3

使用子查询：

SELECT id, (SELECT COUNT() FROM lots WHERE tender_id=tenders.id) AS LotCount FROM tenders;

Answer 4

<强>嗨，这会对你有所帮助......

SELECT * FROM (
SELECT T.*, (SELECT COUNT(*) FROM lots L WHERE L.empid = T.empid) AS 'RecordFound'  
FROM tenders AS T) TendersLots
WHERE RecordFound = 0

谢谢， Vishal Patel

如何统计子行？

4 个答案: