SQL - 每列的条件
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09-09-2020 - |
题
这是一个常规的SQL问题,但我如果你必须知道数据库是Firebird。
我有这个表(简体):
user amount type -------------------- john 25 credit john 20 debit john 5 debit john 15 credit mike 15 credit.
我想使用一个查询的结果如下所示:
user credit debit -------------------- john 40 25 mike 15 NULL.
Where credit = SUM(amount) WHERE type=credit
and debit = SUM(amount) WHERE type=debit
.
基本上我想基于字段的和
提前感谢任何建议。
解决方案
标准SQL将是:
SELECT "user",
SUM(CASE WHEN type='credit' then amount END) as Credit,
SUM(CASE WHEN type='debit' then amount END) as Debit
FROM
"table"
GROUP BY
"user"
. 其他提示
我不确定Firebird是如何做到的,但你能做些什么:
SELECT user,
sum(SELECT amount FROM table AS t2 WHERE t2.user = t1.user AND type="credit" ) AS credit,
sum(SELECT amount FROM table AS t3 WHERE t3.user = t1.user AND type="debit" ) AS debit
FROM table AS t1
GROUP BY user
ORDER BY user
.
我正在引用我认为在postgreSQL中的内容,因为有助于您找到所需的内容。
试试:
SELECT credit.user_name, credit.cre, debit.deb
FROM (SELECT user_name, SUM(amount) cre FROM t WHERE TYPE = 'credit' GROUP BY user_name) credit
LEFT OUTER JOIN (SELECT user_name, SUM(amount) deb
FROM t
WHERE TYPE = 'debit'
GROUP BY user_name) debit
ON (credit.user_name = debit.user_name)
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