[英]calculated field in SQL
我需要添加一個名為“ calc”的字段,其計算公式為
if D.type_id = 1
then calc = calc + D.price
and if D.type_id = 2
then calc = clac - D.price
我到底應該添加什么到下一個SQL代碼中呢?
SELECT T.type_name, D.*, I.name_inout
FROM ((Type T
INNER JOIN Daily D ON (T.type_id=D.type_id))
INNER JOIN Incom I ON (I.id_inout=D.id_inout))
WHERE D.today = DATE()
Order by daily_id
我真的不在乎該字段..我只是在乎“計算”的最終結果,因為我會將最終值傳遞給報表。
如果我正確閱讀了該問題,則需要一個案例說明。
SELECT
case D.type_id
when 1 then calc + D.price
when 2 then calc - D.price
else <<whatever your default is>>
end as CalculatedPrice,
T.type_name, D.*, I.name_inout
FROM (
(
Type T
INNER JOIN Daily D ON (T.type_id=D.type_id)
)
INNER JOIN Incom I ON (I.id_inout=D.id_inout))
WHERE D.today = DATE()
Order by daily_id
如果要使用公式計算得出的價格總和,則需要一個包裝表,如下所示:
select sum(dtA.CalculatedPrice)
From (
SELECT
case D.type_id
when 1 then calc + D.price
when 2 then calc - D.price
else <<whatever your default is>>
end as CalculatedPrice,
T.type_name, D.*, I.name_inout
FROM (
(
Type T
INNER JOIN Daily D ON (T.type_id=D.type_id)
)
INNER JOIN Incom I ON (I.id_inout=D.id_inout))
WHERE D.today = DATE()
) dtA
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