SQLite Query没有得到实际计数

Question

我在计算特定地点的乘客和行李总数时遇到问题。

这是我的表enter image description here

但我的query显示总乘客总是2，

enter image description here

最后，这是query

select
    ticket_placeto,
    (select count(*) as count from tickets where passenger_type <> 'Baggage' group by ticket_placeto)as Pass ,
    ifnull((select count(*) as count from tickets where passenger_type = 'Baggage' group by ticket_placeto),0) as Baggage
from tickets

Answer 1

将您的查询改为使用条件聚合：

SELECT
    ticket_placeto,
    COUNT(CASE WHEN passenger_type <> 'Baggage' THEN 1 END) AS Pass,
    COUNT(CASE WHEN passenger_type =  'Baggage' THEN 1 END) AS Baggage
FROM tickets
GROUP BY ticket_placeto;

这里的想法是，对于每个ticket_placeto组，您希望根据乘客类型采取两个条件计数。