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

MongoDB document update: 1. Can be to delete the original document and then insert an updated new document into the database; 2. Use modifiers to modify document properties in the original document based on the original document.

The following is the main description of using the update method based on the original document with modifiers to modify the document content:

The modified data structure includes simple properties, arrays, and nested documents in the document.

1.$set modifier: lets you specify the value of a key in the document and create it if the key does not exist.

To modify the following documents:

> db.c1.find ({"name": "user3"})

{"_ id": ObjectId ("4fc145e3703fa637a073651b"), "name": "user3", "age": 16}

Modify "name" to "user16": > db.c1.update ({"age": 16}, {"$set": {"name": "user16"}})

> db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "age": 16, "name": "user16"}

Add a book to the document where the user is user16:

> db.c1.update ({"age": 16}, {"$set": {"book": "love story"}); > db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "age": 16, "book": "love story", "name": "user16"}

Added the "book" attribute and added a book.

2.$unset modifier: corresponding to $set, you can remove an attribute value.

To delete the "book" attribute from the above document, use:

Db.c1.update ({"age": 16}, {"$unset": {"book": 1}}); the result is:

> db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "age": 16, "name": "user16" where the "book" attribute is deleted, and "1" removes the book attribute.

3. Use $set,$unset to modify nested documents:

Nested documents as follows: {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "108991"}, "age": 16, "name": "user16"}

Modify the zip attribute to "111111": > db.c1.update ({"age": 16}, {"$set": {"address.zip": "111111"}}); > db.c1.find ({"age": 16}) {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "111111"}, "age": 16, "name": "user16"}

Note that don't forget to use the "$set" modifier when modifying the document, otherwise the original document will be replaced by {"address.zip": "111111"}.

4. Array modifier: modifications to an array, generally including: adding element values, deleting element values.

1)。 First add an array to a document, such as here:

Db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "111111"}, "age": 16, "name": "user16"}

Add a key-value pair of "luckyNumber": [1]. You can do this using the previous $set.

> db.c1.update ({"age": 16}, {"$set": {"luckyNumber": [1mem8: 0]}})

> db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "111111"}, "age": 16, "luckyNumber": [1,8,0], "name": "user16"}

2). $push modifier: press a number into the "lucyNumber". Use this modifier to append a number to the end of the array.

For example: db.c1.update ({"age": 16}, {"$push": {"luckyNumber": 9}}); > db.c1.find ({"age": 16}) {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "111111"}, "age": 16, "luckyNumber": [1,8,0,9], "name": "user16"}

Among them, luckyNumber has an extra number 9. If you continue to use db.c1.update ({"age": 16}, {"$push": {"luckyNumber": 9}}); there will be another 9. (omitted here).

3). $addToSet modifier: treats an array as a collection similar to set, in which the same values cannot be stored.

If you use db.c1.update ({"age": 16}, {"$addToSet": {"luckyNumber": 9}}) in the document of 2), the result will be:

Db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b"), "address": {"location": "linkin street no5", "zip": "111111"}, "age": 16, "luckyNumber": [1,8,0,9], "name": "user16"}

Among them, luckyNumber still has only one 9.

4). Pop array data pop-up: {"$pop": {key:1}} pop-up array tail data, {"$pop": {key:-1}} pop-up array header data

To pop up the last number "9" of luckyNumber:

> db.c1.update ({"age": 16}, {"$pop": {"luckyNumber": 1}); > db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b")

"address": {"location": "linkin street no5", "zip": "111111"}

"age": 16

"luckyNumber": [1,8,0]

"name": "user16"}

The first digit in the pop-up luckyNumber is 1: > db.c1.update ({"age": 16}, {"$pop": {"luckyNumber":-1}}); > db.c1.find ({"age": 16}); {"_ id": ObjectId ("4fc145e3703fa637a073651b")

"address": {"location": "linkin street no5", "zip": "111111"}

"age": 16

"luckyNumber": [8,0]

"name": "user16"}

One of them was popped up.

These are the most basic operations for updating the basic and array properties of the document.

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