如何在单个SQL语句（MySQL）中组合if语句？ [英] How to combine if statements within a single SQL statement (MySQL)?

问题描述

大家好，



我坚持使用包含以下计算的SQL语句：



我在我的数据库中有三个表foto

1.rates（rate_id，price，frequency），2.rate_changes（old_rate_id，new_rate_id，photographer_id）和付款（创建，amount_net）



此外，我想根据价格频率计算每月的amount_net，但我不确切知道该怎么做：

hi everyone,

I´m stuck on a SQL statement which contains the following calculation:

I have three tables in my database foto
1.rates (rate_id, price, frequency),2.rate_changes (old_rate_id, new_rate_id, photographer_id) and payments (created, amount_net)

Further, I want to calculate the amount_net per month depending on the rate frequency but I dn´t know exactly how to do it:

SELECT sum(
if foto.rates.frequency = 1 then (sum foto.payments.amount_net(month x))
elseif foto.rates.frequency = 3 then (foto.payments.amount_net (month x)/foto.rates.frequency) And foto.payments.amount_net (month x-2)+foto.payments.amount_net (month x)/foto.rates.frequency, foto.payments.amount_net (month x-1) + foto.payments.amount_net (month x)/foto.rates.frequency

elseif foto.rates.frequency = 6 then..(the same calculation as in the case before)
elseif foto.rates.frequency = 12 then..(the same calculation as in the cases before))

End

非常感谢您的帮助！

Thanks a lot in advance for your help!

推荐答案

您好，



如何尝试使用某个功能？这对你想要达到的结果很有帮助。

Hello,

How about trying to use a function? That would be helpful in the result you want to achieve.

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