我需要制作两个不同的AVG列，但似乎无法让它工作

Question

SELECT AVG(goals1) FROM matches
WHERE cid='1'
(SELECT AVG(goals2) FROM matches
WHERE cid='2')
;

Answer 1

SELECT AVG(goals1) AvgCid1, (SELECT AVG(goals2) FROM matches WHERE cid='2') AvgCid2
FROM matches
WHERE cid='1'

Answer 2

在这些语句之间添加UNION：

SELECT AVG(goals1) FROM matches
WHERE cid='1'
UNION
SELECT AVG(goals2) FROM matches
WHERE cid='2'

您可能还需要为列命名。

Answer 3

这个怎么样？

SELECT * FROM
(SELECT AVG(goals1) AS goals1 FROM matches WHERE cid='1') t1
full outer join
(SELECT AVG(goals2) AS goals2 FROM matches WHERE cid='2') t2
ON t1.goals1 <> t2.goals2;