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Alexey Starinsky's questions

Martin Hope
Alexey Starinsky
Asked: 2025-03-07 22:18:18 +0800 CST
  • 6

我orders在 SQLite 数据库中有一个表：

CREATE TABLE orders
(
    clientId INTEGER NOT NULL,
    listId INTEGER,
    exchangeId NOT NULL,
    marketId NOT NULL,
    id INTEGER NOT NULL,
    accountType NOT NULL,
    clientGuid NOT NULL,
    side NOT NULL,
    type NOT NULL,
    status NOT NULL,
    price NOT NULL,
    stopPrice NOT NULL,
    amount NOT NULL,
    filled NOT NULL,
    cost NOT NULL,
    createTime NOT NULL,
    updateTime NOT NULL,
    PRIMARY KEY(clientId)
);

当我创建一条记录、删除它然后创建另一条新记录时，我得到了相同的 clientId (14443)：

SQL> INSERT INTO orders (listId, exchangeId, marketId, id, accountType, clientGuid, side, type, status, price, stopPrice, amount, filled, cost, createTime, updateTime) VALUES (19, 'myexchange', 'mymarket', 1163221156, 0, '93c39dd5-bc89-422a-b5e0-a34289ccff44', 0, 0, 1, 778856, 0, 160, 0, 0, 1741356070112000000, 1741356070112000000);


SQL> select * from orders where marketid='mymarket';

(14443, 19, 'myexchange', 'mymarket', 1163221156, 0, '93c39dd5-bc89-422a-b5e0-a34289ccff44', 0, 0, 1, 778856, 0, 160, 0, 0, 1741356070112000000, 1741356070112000000)

SQL> DELETE FROM orders WHERE clientId=14443;


SQL> INSERT INTO orders (listId, exchangeId, marketId, id, accountType, clientGuid, side, type, status, price, stopPrice, amount, filled, cost, createTime, updateTime) VALUES (19, 'myexchange', 'mymarket', 1163221156, 0, '93c39dd5-bc89-422a-b5e0-a34289ccff44', 0, 0, 1, 778856, 0, 160, 0, 0, 1741356070112000000, 1741356070112000000);


SQL> select * from orders where marketid='mymarket';

(14443, 19, 'myexchange', 'mymarket', 1163221156, 0, '93c39dd5-bc89-422a-b5e0-a34289ccff44', 0, 0, 1, 778856, 0, 160, 0, 0, 1741356070112000000, 1741356070112000000)

但是文档中有以下内容：

为新行选择的 ROWID 至少比同一张表中曾经存在过的最大 ROWID 大 1 。

所以根据clientId重新创建的记录的文档应该是 14444，对吗？

如果已删除的订单之一错误地保留在应用程序中的某个位置，则新clientId订单与先前删除的订单相匹配的事实clientId会导致潜在的错误。clientId

有没有办法让 SQLite 生成唯一的clientId？

sqlite
Martin Hope
Alexey Starinsky
Asked: 2025-02-27 05:19:19 +0800 CST
  • 5

我有两张桌子：

CREATE TABLE new_orders
(
    clientId INTEGER NOT NULL,
    exchangeId NOT NULL,
    marketId NOT NULL,
    id INTEGER NOT NULL,
    accountType NOT NULL,
    listId INTEGER NOT NULL,
    clientGuid NOT NULL,
    side NOT NULL,
    type NOT NULL,
    status NOT NULL,
    price NOT NULL,
    stopPrice NOT NULL,
    amount NOT NULL,
    filled NOT NULL,
    cost NOT NULL,
    createTime NOT NULL,
    updateTime NOT NULL,
    PRIMARY KEY(clientId)
)

CREATE TABLE old_orders
(
    exchangeId NOT NULL,
    marketId NOT NULL,
    id INTEGER NOT NULL,
    accountType NOT NULL,
    listId INTEGER NOT NULL,
    clientId NOT NULL,
    side NOT NULL,
    type NOT NULL,
    status NOT NULL,
    price NOT NULL,
    stopPrice NOT NULL,
    amount NOT NULL,
    filled NOT NULL,
    cost NOT NULL,
    createTime NOT NULL,
    updateTime NOT NULL,
    PRIMARY KEY(accountType, marketId, id) WITHOUT ROWID
)

当我尝试将所有记录从 old_orders 插入到 new_orders 并clientId使用以下查询自动生成新记录时：

    INSERT INTO new_orders 
        SELECT clientId AS clientGuid, exchangeId, marketId, id, accountType, listId, side, type, status, price, stopPrice, amount, filled, cost, createTime, updateTime 
        FROM old_orders;

但查询失败并出现以下错误：

表 new_orders 有 17 列，但提供了 16 个值

如何实现这个功能？

new_orders.clientId是自动增量列，对吧？那么为什么这个查询不起作用？

sqlite
Martin Hope
Alexey Starinsky
Asked: 2023-10-06 19:29:37 +0800 CST
  • 6

有一个答案解释了为什么 std::find_if 采用 value 谓词。

但是如果我定义自己的函数并将谓词作为参数怎么办？

例如，考虑以下为每个元组元素调用给定函数的函数：

template <typename... Args, typename Func, std::size_t... index>
constexpr void for_each(const std::tuple<Args...>& t, Func&& f, std::index_sequence<index...>)
{
    (f(std::get<index>(t)), ...);
}

template <typename... Args, typename Func>
constexpr void for_each(const std::tuple<Args...>& t, Func&& f)
{
    for_each(t, f, std::index_sequence_for<Args...>{});
}

这段代码中f是通过右值引用传递的，这是正确的方法吗？

使用示例：

auto t = std::make_tuple(5, std::string(""));

for_each(t, [](auto& field)
{
    std::cout << field << std::endl;
});

不应该有吗const Func&？

c++
Martin Hope
Alexey Starinsky
Asked: 2023-08-30 21:34:22 +0800 CST
  • 5

我运行cmake如下：

cmake . -G Ninja -D CMAKE_PREFIX_PATH=~/libs/QT6.5d -DCMAKE_WARN_DEPRECATED=OFF

但在使用 GCC12 构建我的项目时收到以下警告：

  /usr/include/c++/12/backward/backward_warning.h:32:2: warning: #warning This file includes at least one deprecated or antiquated header which may be removed without further notice at a future date. Please use a non-deprecated interface with equivalent functionality instead. For a listing of replacement headers and interfaces, consult the file backward_warning.h. To disable this warning use -Wno-deprecated. [-Wcpp]
     32 | #warning \
        |  ^~~~~~~

为什么没有CMAKE_WARN_DEPRECATED效果？

运行 cmake-Wno-deprecated也没有帮助。

cmake . -G Ninja -D CMAKE_PREFIX_PATH=~/libs/QT6.5d -Wno-deprecated
gcc