对于每个用户,我想产生一个聚合结果。然而,我一直遇到子查询返回多个结果的问题。
SELECT **[user]**,
((SELECT SUM(amount)
FROM transactions
WHERE [user] = **[user]**
AND [type] = 'credit' ) -
(SELECT SUM(amount)
FROM transactions
WHERE [user] = **[user]**
AND [type] = 'debit' ))
FROM transactions
我该如何从开始的 select
中获取 user
,然后将其作为变量 user
在子查询中进行操作?