对两个 SQLite 列求和，当它们是子查询时

Question

我有 table 的收据。每个人都与一项服务相关联，每个人都有义务为此支付同等费用，除非他们被分配了额外费用，可以是 activated/deactivaded (0/1)。所以我使用子查询来获取他们必须支付的额外金额，只有在该费用有效时； table'fees'包含user_id，service_id ，额外金额和活动标志。然后，我应该得到每人的总数，将额外费用（如果有的话）加到小计中（收据总额减去任何有效的额外费用，然后除以有义务捐款的人数）。

SELECT
    P.nombre AS person,
    S.nombre AS service,
    (
        SELECT TOTAL(C.value)
        FROM fees C
        WHERE C.user_id = P.id AND C.service_id = O.service_id AND C.active = 0
    ) AS fee,
    IFNULL(NULL, 23333) AS subtotal,
    (fee + subtotal) as total
FROM receipts R
    LEFT JOIN obligations O ON O.service_id = R.service_id
    LEFT JOIN persons P ON O.user_id = P.id
    LEFT JOIN services S ON O.service_id = S.id
WHERE R.id = 3 AND O.active = 0;

注意：23333（小计）将被替换为“？”然后我将作为参数传递给 Golang 执行查询，结果是我已经从另一个函数

这一行出现问题

(fee + subtotal) as total

输出：没有这样的列：费用

如果我运行没有该行的查询，它实际上会 return 一个 table 包含有效的额外费用和小计，但我在尝试创建一个添加这两个值的最后一列。

谢谢！

编辑

按照 Stefan 的建议，这是我用来创建 tables 的语句：

CREATE TABLE IF NOT EXISTS persons (id INTEGER PRIMARY KEY, name TEXT NOT NULL, active INTEGER DEFAULT 0); CREATE UNIQUE INDEX per_nom_uindex on persons (name)

CREATE TABLE IF NOT EXISTS services (id INTEGER PRIMARY KEY, name TEXT NOT NULL, active INTEGER  DEFAULT 0); CREATE UNIQUE INDEX ser_nom_uindex on services (name)

CREATE TABLE IF NOT EXISTS receipts (id INTEGER PRIMARY KEY, y INTEGER NOT NULL, m INTEGER NOT NULL, service_id INTEGER NOT NULL, amount INTEGER NOT NULL, FOREIGN KEY (service_id) REFERENCES services (id))

CREATE TABLE IF NOT EXISTS fees (id INTEGER PRIMARY KEY, person_id INTEGER NOT NULL, service_id INTEGER NOT NULL, amount INTEGER NOT NULL, active INTEGER DEFAULT 0, FOREIGN KEY(person_id) REFERENCES persons(id), FOREIGN KEY(service_id) REFERENCES services(id))

CREATE TABLE IF NOT EXISTS obligations (id INTEGER PRIMARY KEY, person_id INTEGER NOT NULL, service_id INTEGER NOT NULL, active INTEGER DEFAULT 0, FOREIGN KEY(person_id) REFERENCES persons(id), FOREIGN KEY(service_id) REFERENCES services(id))

Answer 1

考虑将子查询从 SELECT 移动到 JOIN 子句（通常称为派生 table）并使用 GROUP BY 聚合对 user_id 和 service_id。这样做，您可以根据需要引用该列，甚至可以避免按行聚合（除非 SQLite 引擎在后台将其作为单个聚合运行）。

SELECT
    P.nombre AS person,
    S.nombre AS service,
    C.fee,                                  -- REFERENCE SUBQUERY COLUMN
    IFNULL(?, 23333) AS subtotal,
    C.fee + IFNULL(?, 23333) as total       -- REPEAT NEEDED EXPRESSION
FROM receipts R
    LEFT JOIN obligations O 
        ON O.service_id = R.service_id 
    LEFT JOIN persons P  
        ON O.user_id = P.id 
        AND O.active = 0                    -- MOVED FROM WHERE CLAUSE
    LEFT JOIN services S 
        ON O.service_id = S.id
    LEFT JOIN (
        SELECT user_id,
               service_id, 
               TOTAL(value) AS fee
        FROM fees
        WHERE active = 0
        GROUP BY user_id,
                 service_id
    ) C ON C.user_id = P.id
        AND C.service_id = O.service_id
    WHERE R.id = 3

对两个 SQLite 列求和，当它们是子查询时

Sum two SQLite columns, when they're subqueries

sql

sqlite