db.c_user.insertOne({

     name: "ljm",

     pwd: "123456"

 }); //插入一个

 db.c_user.insertMany([{

     item: "wjl",

     age: "25",

     tags: ["blank", "red"],

     size: {

         h: 14,

         w: 21

     }

 },

 {

     item: "ljm",

     age: "18",

     tags: ["blank", "red"],

     size: {

         h: 14,

         w: 21

     }

 }]) ;//插入多个

 db.c_type.insertMany([{

     item: "wjl",

     age: "25",

     tags: ["blank", "red"],

     size: {

         h: 14,

         w: 21

     }

 },

 {

     item: "ljm",

     age: "18",

     tags: ["blank", "red"],

     size: {

         h: 14,

         w: 21

     }

 }]) ;//插入多个

 db.getCollection("c_user").find({}) ;

 db.getCollection("c_user").find();

 db.c_user.find({

     name: "ljm"

 }) ;//Key:value 查询，相当于where name = ""

 db.getCollection("c_type").find({});

 db.c_user.find({

     name: "wjl",

     age: {

         $lt: 30

     }

 }); // where .. and ... ,lt < ; gt >

 db.c_user.find({

     $or: [{

         name: "wjl"

     },

     {

         age: {

             $lt: 30

         }

     }]

 }); // where ... or ... 

 db.c_user.find({

     name: "wjl",

     $or: [{

         age: {

             $lt: 30

         }

     },

     {

         name: /^m/

     }]

 }); // where and .. or ..

 db.c_user.find({

     name: {

         $in: ["wjl", "ljm"]

     }

 }) ;//where in

 db.c_user.updateOne({

     "_id": ObjectId("5d034c0de20035e8e98d684a")

 },

 {

     $set: {

         pwd: "1315565452",

         name: "zhangsan"

     }

 }); //修改一个

 db.c_user.updateMany({

     name: "wjl"

 },

 {

     $set: {

         pwd: "1315565452",

         name: "zhangsan"

     }

 }); //修改多个

 db.c_user.replaceOne({

     name: "ljm"

 },

 {

     name: "ljm",

     age: "80"

 }) ;//替换一个

 db.c_user.deleteOne({

     "_id": ObjectId("5d034fdee20035e8e98d6850")

 }) ;//删除一个