MongoDB basic Operations (ii)-(CRUD)

MongoDB's shell operation data, used to create, read, update, delete operations.

1. Create

The Insert function is used to create a document inside the collection.

example, create a local variable post, which is a JavaScript object representing the document, with the title, content, and date keys.

> post = {"title": "My Blog post",

... "Content": "Here ' s my blog post",

... "Date": New Date ()}

{

"title": "My Blog Post",

"Content": "Here ' s my blog post",

"Date": Isodate ("2015-02-02t05:04:55.861z")

}

> DB

Test

Use the Insert method to save to the collection blog, note that at this time the blog does not exist.

> Db.blog.insert (POST)

Writeresult ({"ninserted": 1})

2. Read

The Find () function reads all the documents in the collection:

> Db.blog.find ();

{"_id": ObjectId ("54cf05c00eb7b5f5718da826"), "title": "My Blog Post", "Conte

NT ":" Here's my blog post "," Date ": Isodate (" 2015-02-02t05:04:55.861z ")}

If you want to view only one document, use FindOne ()

> Db.blog.findone ();

2015-02-02t13:10:15.365+0800 typeerror:property ' FindOne ' of object Test.blog I

s not a function

> Db.blog.findOne ();

{

"_id": ObjectId ("54cf05c00eb7b5f5718da826"),

"title": "My Blog Post",

"Content": "Here ' s my blog post",

"Date": Isodate ("2015-02-02t05:04:55.861z")

}

3. Update

Update accepts at least two parameters: one is to update the document's qualifications, and the other is the new document. If you decide to add a comment to a previously written article, you need to add a new key, and the corresponding value is an array of comments:

Modify the variable post to add the "comment" key:

> post.comments = [];

[ ]

Perform an update

> db.blog.update ({"title": "My blog Post"},post)

Writeresult ({"nmatched": 1, "nupserted": 0, "nmodified": 1})

> Db.blog.find ();

{"_id": ObjectId ("54cf05c00eb7b5f5718da826"), "title": "My Blog Post", "Conte

NT ":" Here ' s my blog post "," Date ": Isodate (" 2015-02-02t05:04:55.861z ")," Comm

Ents ": []}

> Db.blog.findOne ();

{

"_id": ObjectId ("54cf05c00eb7b5f5718da826"),

"title": "My Blog Post",

"Content": "Here ' s my blog post",

"Date": Isodate ("2015-02-02t05:04:55.861z"),

"Comments": []

}

4. Delete

Remove is used to permanently delete a document from the database and, in the case of non-applicable parameters, it deletes all documents within a collection, or it can accept a document to specify restrictions:

> Db.blog.remove ({"title": "My blog Post"});

Writeresult ({"nremoved": 1})

> Db.blog.find ();

>

MongoDB basic Operations (ii)-(CRUD)