> db.customer.find().pretty() { "_id" : ObjectId("559bb1d1d39f0dcac2658f8e"), "cust_id" : "abc123", "ord_date" : ISODate("2012-10-03T16:00:00Z"), "status" : "A", "price" : 25, "items" : [ { "sku" : "mmm", "qty" : 5, "price" : 2.5 }, { "sku" : "nnn", "qty" : 5, "price" : 2.5 } ] } { "_id" : ObjectId("559bb1ead39f0dcac2658f8f"), "cust_id" : "abc123", "ord_date" : ISODate("2012-10-03T16:00:00Z"), "status" : "B", "price" : 30, "items" : [ { "sku" : "mmm", "qty" : 6, "price" : 3.5 }, { "sku" : "nnn", "qty" : 6, "price" : 3.5 } ] } { "_id" : ObjectId("559bb200d39f0dcac2658f90"), "cust_id" : "abc123", "ord_date" : ISODate("2012-10-03T16:00:00Z"), "status" : "C", "price" : 35, "items" : [ { "sku" : "mmm", "qty" : 7, "price" : 4.5 }, { "sku" : "nnn", "qty" : 7, "price" : 4.5 } ] } > db.customer.find({"items.qty":6},{"items.$":1}).pretty() //只返回和查询条件匹配的那一个元素 { "_id" : ObjectId("559bb1ead39f0dcac2658f8f"), "items" : [ { "sku" : "mmm", "qty" : 6, "price" : 3.5 } ] }

查询匹配的内嵌文档，你也可以直接查询，如：

> db.customer.find({"items.qty":6}).pretty() { "_id" : ObjectId("559bb1ead39f0dcac2658f8f"), "cust_id" : "abc123", "ord_date" : ISODate("2012-10-03T16:00:00Z"), "status" : "B", "price" : 30, "items" : [ { "sku" : "mmm", "qty" : 6, "price" : 3.5 }, { "sku" : "nnn", "qty" : 6, "price" : 3.5 } ] }

对应你上面的查询实现：

> db.customer.find({"_id":ObjectId("559bb1ead39f0dcac2658f8f"),items: {'$elemMatch': {'sku': "mmm"}}},{"items.$":1}).pretty() { "_id" : ObjectId("559bb1ead39f0dcac2658f8f"), "items" : [ { "sku" : "mmm", "qty" : 6, "price" : 3.5 } ] }

db.test.find({_id: ObjectId('55e99a2190df7a911d6ed1f1'), list: {'$elemMatch': {'aa': 1}}},{"list.$":1}).pretty()

首先 你用mongodb 你得明白 monggodb是nosql
然后 mongo的collection中存储的是document
最后 你要知道 find 返回的值一定是一个document的集合 也就是个array

所以你说的 基本上无法实现

只需要在find中填写你需要的查询的条件即可。更多详情，请查阅mongodb官网

使用 $ 操作符能返回一个 多个的话 没门