thousandsofthem's questions

尝试使行保持一致，然后引用之前的行。

CREATE TABLE transactions (
    id         int     PRIMARY KEY
       GENERATED BY DEFAULT AS IDENTITY,

    account_id bigint  REFERENCES account,
    change     integer NOT NULL,
    balance    integer NOT NULL,
)

来自客户端的查询基本上是

SELECT balance
FROM transactions
WHERE account_id = X
ORDER BY id DESC
LIMIT 1;

INSERT INTO transactions (account_id, change, balance)
VALUES (X, 100, $balance + 100);

此代码将在并发插入时产生不正确的结果。那么，问题是如何让余额计算永远正确呢？

会INSERT INTO ... SELECT(...)够吗？