db.collection.find(query_condition, projection_field):
query_condition：查询的条件，可以设置单个条件、多个条件（and、or）、对于field可以进行类似shell编程中的关系运算符，但是并不完全相同。例如：在shell中不小于即为：$ge ，而在mongoDB中需要使用$gte。
projection_field：设定返回的field；
???自动生成的ID是必须要进行设定说明，如果不设定是默认为1则返回，设定为0，则不返回；?
? ?其他filed，如果都不设置即默认为1进行全部返回，如果任何field设置为1，其他字段则默认为0，不返回。
关于查询条件使用的案例
- 关于关系运算符：
关于运算符的说明
| 关系运算符 | 说明 | | $eq | 等于 | | $ne | 不等于 | | $gt | 大于 | | $gte | 不小于 | | $lt | 小于 | | $lte | 不大于 | - 依赖于上面的顺序，现在举例说明
全量的文档：
> db.localfindb.localfidb.localfdb.localdb.local.find()db.local.find()
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
>?
提取年龄=90的
>db.local.find({"age":{$eq:90}})
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
>?
> db.local.find({"age":90})
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
>?
提取年龄不等于90的
> db.local.find({"age":{$ne:90}})db.local.find({"age":{$ne:90}})
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
>?
提取年龄大于90的
> db.local.find({"age":{$gt:90}})db.local.find({"age":{$gt:90}})
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
>?
提取年龄不小于90的
> db.local.find({"age":{$gte:90}})db.local.find({"age":{$gte:90}})
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
>?
>?
提取年龄小于90的
> db.local.find({"age":{$lt:90}})db.local.find({"age":{$lt:90}})
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
>?
提取年龄不大于90的
> db.local.find({"age":{$lte:90}})db.local.find({"age":{$lte:90}})
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
>?
关于and条件的使用
全量文档如下：
> db.localfindb.localfidb.localfdb.localdb.local.find()db.local.find()
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
> db.local.find({$and:[{"age":100,"sex":"femal"}]})
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
>?
>db.local.find({"age":100,"sex":"femal"})
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
关于or条件的使用
全量文档如下：
> db.localfindb.localfidb.localfdb.localdb.local.find()db.local.find()
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
> db.local.find({$or:[{"age":70},{"sex":"man"}]})db.local.find({$or:[{"age":70},{"sex":"man"}]})
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
>?
>?
关于and条件和or条件的联合使用
> db.local.find({"age":100,$or:[{"sex":"man"},{"sex":"femal"}]})
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
关于查询字段的使用样例：
-
查询全部的文档全部的field：
> db.local.find()
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
> db.local.find({},{})db.local.find({},{})
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "name" : "zhengzw", "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "name" : "zhengzw", "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "name" : "zhengzw", "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "name" : "zhengzw", "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "name" : "zhengzw", "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "name" : "zhengzw", "age" : 110, "sex" : "femal" }
>?
-
查询全部文档中的两个field（显示ID）
> db.local.find({},{"age":1,"sex":1} ?)
{ "_id" : ObjectId("6139d43dbae7eecd0acf51c6"), "age" : 100 }
{ "_id" : ObjectId("6139d4e7bae7eecd0acf51c7"), "age" : 100, "sex" : "man" }
{ "_id" : ObjectId("6139f3b5ea30f42c635791d6"), "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d7"), "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f3deea30f42c635791d8"), "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f40dea30f42c635791d9"), "age" : 90, "sex" : "femal" }
{ "_id" : ObjectId("6139f41bea30f42c635791da"), "age" : 70, "sex" : "femal" }
{ "_id" : ObjectId("6139f42bea30f42c635791db"), "age" : 100, "sex" : "femal" }
{ "_id" : ObjectId("6139f446ea30f42c635791dc"), "age" : 110, "sex" : "femal" }
-
查询全部文档中的两个field（不显示ID） >db.local.find({},{"_id":0,"age":1,"sex":1})
{ "age" : 100 }
{ "age" : 100, "sex" : "man" }
{ "age" : 100, "sex" : "femal" }
{ "age" : 100, "sex" : "femal" }
{ "age" : 100, "sex" : "femal" }
{ "age" : 90, "sex" : "femal" }
{ "age" : 70, "sex" : "femal" }
{ "age" : 100, "sex" : "femal" }
{ "age" : 110, "sex" : "femal" }
>
|