Shulou(Shulou.com)06/01 Report--

MongoDB中使用find来进行查询，返回一个集合中的文档的子集;

返回文档集合blog中的所有文档：

> db.post.find() { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30, "sex" : 1, "school" : "marry" } { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" } >

返回指定的文档：

> db.post.find({"id":1}) { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" } >

返回指定的键值：

> db.post.find({},{"id":1,"age":1}) { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "age" : 30 } { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "age" : 30 } >

默认总是会返回"_id"键，使用下面的方法可以不返回" _id"键：

> db.post.find({},{"id":1,"age":1,"_id":0}) { "id" : 2, "age" : 30 } { "id" : 1, "age" : 30 } >

可以将多个条件组合在一起，例如查询名字为"Joe"且ID为1的文档：

> db.post.find({"name":"joe"}) { "_id" : ObjectId("54a530c3ff0df3732bac1681"), "id" : 2, "name" : "joe", "age" : 30, "sex" : 1, "school" : "marry" } { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" } > db.post.find({"name":"joe","id":1}) { "_id" : ObjectId("54a530c3ff0df3732bac1680"), "id" : 1, "name" : "joe", "age" : 30, "comments" : [ "test2", "test9", "test5" ], "sex" : 1, "school" : "marry" } >

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