mysql - 如何在不使用 union mysql 的情况下从一个查询中的两个不同表求和

Question

SELECT SUM(amount_paid) AS total_session FROM session 
WHERE session.date = '2016-02-03' AND session.payment_status = 'PAID'
UNION 
SELECT SUM(amount_paid) AS total_subscription FROM subscription 
WHERE subscription.date_enrolled = '2016-02-03'  AND subscription.payment_status = 'PAID'

我只想在别名为 total_session 和 total_subscription 的两个不同列中显示结果。我怎样才能使用 union 做到这一点？

Answer 1

代替 UNION，将每个查询作为子查询放在主 SELECT

中

SELECT 
    (SELECT SUM(amount_paid) FROM session 
    WHERE session.date = '2016-02-03' AND session.payment_status = 'PAID') AS total_paid,
    (SELECT SUM(amount_paid) FROM subscription 
    WHERE subscription.date_enrolled = '2016-02-03'  AND subscription.payment_status = 'PAID') AS total_subscription