mongodb常规操作语句

 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