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例子
聚合管道允许 MongoDB 提供与 SQL 中许多 common 数据聚合操作相对应的本机聚合功能。
以下 table 概述了 common SQL 聚合术语,函数和概念以及相应的 MongoDB 聚合运算符:
有关所有聚合管道和表达式 operators 的列表,请参阅聚合管道快速参考。
也可以看看
SQL 到 MongoDB 映射图表](SQL-to-Aggregation-Mapping-Chart.md)
以下 table 提供了 SQL 聚合 statements 和相应的 MongoDB statements 的快速 reference。 table 中的示例假定以下条件:
SQL 示例假设两个表orders
和order_lineitem
由order_lineitem.order_id
和orders.id
列连接。
MongoDB 示例假设一个集合orders
包含以下原型的文档:
{cust_id: "abc123",ord_date: ISODate("2012-11-02T17:04:11.102Z"),status: 'A',price: 50,items: [ { sku: "xxx", qty: 25, price: 1 },{ sku: "yyy", qty: 25, price: 1 } ]}
SQL语句 | MongoDB语句 | 描述 |
SELECT COUNT(*) AS count FROM orders | db.orders.aggregate( [ { $group: { _id: null, count: { $sum: 1 } } } ] ) | 计算来自 |
SELECT SUM(price) AS total FROM orders | db.orders.aggregate( [ { $group: { _id: null, total: { $sum: "$price" } } } ] ) |
|
SELECT cust_id, SUM(price) AS total FROM orders GROUP BY cust_id | db.orders.aggregate( [ { $group: { _id: "$cust_id", total: { $sum: "$price" } } } ] ) | 对于每个唯一 |
SELECT cust_id, SUM(price) AS total FROM orders GROUP BY cust_id ORDER BY total | db.orders.aggregate( [ { $group: { _id: "$cust_id", total: { $sum: "$price" } } }, { $sort: { total: 1 } } ] ) | 对于每个唯一 |
SELECT cust_id, ord_date, SUM(price) AS total FROM orders GROUP BY cust_id, ord_date | db.orders.aggregate( [ { $group: { _id: { cust_id: "$cust_id", ord_date: { $dateToString: { format: "%Y-%m-%d", date: "$ord_date" }} }, total: { $sum: "$price" } } } ] ) | 对于每个唯一的 |
SELECT cust_id, count(*) FROM orders GROUP BY cust_id HAVING count(*) > 1 | db.orders.aggregate( [ { $group: { _id: "$cust_id", count: { $sum: 1 } } }, { $match: { count: { $gt: 1 } } } ] ) | 对于具有多个记录的 |
SELECT cust_id, ord_date, SUM(price) AS total FROM orders GROUP BY cust_id, ord_date HAVING total > 250 | db.orders.aggregate( [ { $group: { _id: { cust_id: "$cust_id", ord_date: { $dateToString: { format: "%Y-%m-%d", date: "$ord_date" }} }, total: { $sum: "$price" } } }, { $match: { total: { $gt: 250 } } } ] ) | 对于每个唯一的 |
SELECT cust_id, SUM(price) as total FROM orders WHERE status = 'A' GROUP BY cust_id | db.orders.aggregate( [ { $match: { status: 'A' } }, { $group: { _id: "$cust_id", total: { $sum: "$price" } } } ] ) | 对于状态为 |
SELECT cust_id, SUM(price) as total FROM orders WHERE status = 'A' GROUP BY cust_id HAVING total > 250 | db.orders.aggregate( [ { $match: { status: 'A' } }, { $group: { _id: "$cust_id", total: { $sum: "$price" } } }, { $match: { total: { $gt: 250 } } } ] ) | 对于状态为 |
SELECT cust_id, SUM(li.qty) as qty FROM orders o, order_lineitem li WHERE li.order_id = o.id GROUP BY cust_id | db.orders.aggregate( [ { $unwind: "$items" }, { $group: { _id: "$cust_id", qty: { $sum: "$items.qty" } } } ] ) | 对于每个唯一 |
SELECT COUNT(*) FROM (SELECT cust_id, ord_date FROM orders GROUP BY cust_id, ord_date) as DerivedTable | db.orders.aggregate( [ { $group: { _id: { cust_id: "$cust_id", ord_date: { $dateToString: { format: "%Y-%m-%d", date: "$ord_date" }} } } }, { $group: { _id: null, count: { $sum: 1 } } } ] ) | 计算不同的 |
也可以看看
聚合管道快速参考
译者:李冠飞
校对: