sequelize 子查询作为字段

Question

我正在尝试通过 sequlized 生成这样的查询：

SELECT 
    "Customers"."id", 
    (SELECT SUM("Orders"."amount") FROM "Orders"
     WHERE "Orders"."CustomerId" = "Customers"."id") AS "totalAmount",
    "Customer"."lastName" AS "Customer.lastName",
    "Customer"."firstName" AS "Customer.firstName" 
FROM "Customers" AS "Customer";

我试图避免使用 GROUP BY 子句，因为我有很多字段需要 select 并且我不想按所有字段分组（我认为这效率不高，是吗？不是吗？）

我已经尝试了几种方法来实现 sequelize，包括 {include: ...} 和 {attributes: [[...]]}，但没有任何运气。

有什么想法吗？或者也许我应该使用一个大的 GROUP BY 子句并让所有“常规”字段分组？

Answer 1

您的最佳选择是：

    return Customer.findAll({
        attributes: Object.keys(Customer.attributes).concat([
            [sequelize.literal('(SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id")'), 'totalAmount']
        ])
    });

这看起来像是问题 #1869:

的扩展

Querying on the through model/join table is not possible currently unfortuneatly.

您的问题也与 this one 无关，其中的问题有点像“对于每个关联的用户查询 table”。

查看 test code 的 include 子句，我没有看到任何组选项，这表明此功能没有证据。

解决方案：

当然，您可以只传递“原始”查询：

    return sequelize.query(
        'SELECT *, (SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id") AS "totalAmount" FROM "Customers" AS "Customer";',
        Customer,
        {raw: false}
    );

即给你想要的，又包裹成Customer个实例。

或者，您可以添加一个 returns 另一个承诺的实例方法：

instanceMethods: {
    getOrderSummary: function () {
        return Order.findAll({
            where: {
                CustomerId: this.id
            },
            attributes: [
                [sequelize.fn('SUM', sequelize.col('amount')), 'sum'],
                'CustomerId'],
            group: ['CustomerId']
        });
    }
}

实例方法版本不是很干净，但它工作正常，可能更适合您的情况。

我发现的最佳解决方案是在查询的 attribute 字段中使用 SQL 文字。唯一的缺点是它似乎在 selecting 其他属性上将石板擦干净，并且'*'不会削减它。因此，您需要使用 Object.keys().

进行变通

    return Customer.findAll({
        attributes: Object.keys(Customer.attributes).concat([
            [sequelize.literal('(SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id")'), 'totalAmount']
        ])
    });

尽管如此，它还是很有魅力，您可以将它用于一些更有趣的嵌套 SELECT。 findAll 给了我们正确的：

Executing (default): SELECT "id", "firstName", "lastName", "createdAt", "updatedAt", (SELECT SUM("Orders"."amount") FROM "Orders" WHERE "Orders"."CustomerId" = "Customer"."id") AS "totalAmount" FROM "Customers" AS "Customer";
{ id: 1,
  firstName: 'Test',
  lastName: 'Testerson',
  createdAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  updatedAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  totalAmount: 15 }
{ id: 2,
  firstName: 'Invisible',
  lastName: 'Hand',
  createdAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  updatedAt: Wed Feb 04 2015 08:05:42 GMT-0500 (EST),
  totalAmount: 99 }

顺便说一句，我也尝试过向后做，并在 Order 模型上使用 GROUP BY select 进入 Customer 模型，但这没有用：

    // Doesn't work
    return Order.findAll({
        attributes: [
            [Sequelize.fn('COUNT', '*'), 'orderCount'],
            'CustomerId'
        ],
        include: [
            {model: Customer, attributes: ['id']}
        ],
        group: ['CustomerId']
    });

Answer 2

在 Sequelize 4 中，您可以使用 attributes.include 语法 http://docs.sequelizejs.com/manual/tutorial/querying.html

添加额外的属性

return Customer.findAll({
    attributes: {
        include: [
           [sequelize.literal('(SELECT SUM("Orders"."amount") FROM "Orders" 
            WHERE "Orders"."CustomerId" = "Customer"."id")'), 'totalAmount']
        ]
    }
});

sequelize 子查询作为字段

sequelize subquery as field

sequelize.js