Shulou(Shulou.com)06/01 Report--

MongoDB shell operation data, using create, read, update, delete operation.

1. Create

The insert function is used to create a document into the collection.

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

> 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, and note that blog does not exist at this time.

> 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

3.1

Update accepts at least two parameters: one is to update the qualification of the document, and the other is the new document. Suppose you decide to add comments to a previously written article, you need to add a new key, and the corresponding value is the array where the comments are stored:

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

> post.comments = []

[]

Execute 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": []

}

3.2 use modifiers ("$inc" modifier)

Usually only part of the document needs to be updated, and the use of atomic update modifiers can make this partial update extremely efficient. Update modifiers are special keys that specify complex update operations, such as adjusting, adding, or deleting keys, as well as manipulating arrays or embedded documents.

Let's take a look at the updated example:

> db.people.find ()

{"_ id": ObjectId ("54d08f7f0eb7b5f5718da82a"), "name": "joe", "age": 65}

{"_ id": ObjectId ("54d08fb70eb7b5f5718da82b"), "name": "joe", "age": 20}

{"_ id": ObjectId ("54d08fbd0eb7b5f5718da82c"), "name": "joe", "age": 49}

> db.people.update ({"age": 20}, {"$inc": {"age": 1}})

WriteResult ({"nMatched": 1, "nUpserted": 0, "nModified": 1})

> db.people.find ()

{"_ id": ObjectId ("54d08a1d0eb7b5f5718da828"), "name": "joe", "friends": 32

"enemies": 2}

{"_ id": ObjectId ("54d08f7f0eb7b5f5718da82a"), "name": "joe", "age": 65}

{"_ id": ObjectId ("54d08fb70eb7b5f5718da82b"), "name": "joe", "age": 21}

{"_ id": ObjectId ("54d08fbd0eb7b5f5718da82c"), "name": "joe", "age": 49}

>

4. Delete

Remove is used to permanently delete documents from the database, delete all documents in a collection if the parameter is not applicable, or accept a document to specify constraints:

> db.blog.remove ({"title": "My Blog Post"})

WriteResult ({"nRemoved": 1})

> db.blog.find ()

>

The deletion is permanent and cannot be undone or restored.

Deleting a document is usually quick, but to clear the entire collection, it is faster to delete the collection directly (and then re-index it).

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