MongoDB quick start notes of iii MongoDB insert document operation

MongoDB is a database based on distributed file storage. Written by C++ language. Designed to provide scalable, high-performance data storage solutions for WEB applications.

MongoDB is a product between relational database and non-relational database. It is the most functional and relational database like non-relational database.

This article introduces you to MongoDB's method of inserting documents. Take a look at it

1. The data storage format of the document is BSON, similar to JSON. When MongoDB inserts data, it checks whether there is "_id" in the data. If not, it is generated automatically.

There are two methods for shell operation: insert and save. When a piece of data is inserted with the value "_id" and the same value is already in the collection, it cannot be inserted with insert. When save is used, the data will be updated.

> db.student.drop()
true
> db.student.insert({"_id": 1, "name":"zhangsan", "age": 28})
WriteResult({ "nInserted" : 1 })
> db.student.find()
{ "_id" : 1, "name" : "zhangsan", "age" : 28 }
> db.student.insert({"_id": 1, "name":"zhangsan", "age": 27})
WriteResult({
"nInserted" : 0,
"writeError" : {
"code" : 11000,
"errmsg" : "E11000 duplicate key error collection: zyhdb.student index: _id_ dup key: { : 1.0 }"
}
})
> db.student.find()
{ "_id" : 1, "name" : "zhangsan", "age" : 28 }
> db.student.save({"_id": 1, "name":"zhangsan", "age": 27})
WriteResult({ "nMatched" : 1, "nUpserted" : 0, "nModified" : 1 })
> db.student.find()
{ "_id" : 1, "name" : "zhangsan", "age" : 27 } 

2. Batch insert. The documents on the Internet all say that MongoDB does not support batch insert.

> db.student.insert([{"_id": 2, "name": "lisi"},{"_id": 3, "name": "wangwu"}, {"_id": 4, "name": "zhaoliu", "age": 28}])
BulkWriteResult({
"writeErrors" : [ ],
"writeConcernErrors" : [ ],
"nInserted" : 3,
"nUpserted" : 0,
"nMatched" : 0,
"nModified" : 0,
"nRemoved" : 0,
"upserted" : [ ]
})
> db.student.find()
{ "_id" : 1, "name" : "zhangsan", "age" : 27 }
{ "_id" : , "name" : "lisi" }
{ "_id" : , "name" : "wangwu" }
{ "_id" : 4, "name" : "zhaoliu", "age" : 28 } 

3. Cyclic insertion:

> for(var i=; i<; i++){db.fortest.insert({num: i})}
WriteResult({ "nInserted" : })
> db.fortest.find()
{ "_id" : ObjectId("eceadaeabab"), "num" : 0}
{ "_id" : ObjectId("eceadaeabab"), "num" : 1}
{ "_id" : ObjectId("eceadaeabab"), "num" : 2}
{ "_id" : ObjectId("eceadaeabab"), "num" : 3}
{ "_id" : ObjectId("eceadaeabab"), "num" : 4}
{ "_id" : ObjectId("eceadaeababa"), "num" : 5}
{ "_id" : ObjectId("eceadaeababb"), "num" : 6}
{ "_id" : ObjectId("eceadaeababc"), "num" : 7}
{ "_id" : ObjectId("eceadaeababd"), "num" : 8}
{ "_id" : ObjectId("eceadaeababe"), "num" : 9}

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