MongoDB Learning: Document manipulation

In the previous chapter, there is a way to insert a document by inserting it . If the collection is not in the database,MongoDB automatically creates the set and inserts the document

Find all the collection data using the Find method

> Db.maple.find ()

{"_id": ObjectId ("5a35d6278ef76f6d57aae92c"), "name": "ZHF"

You can also define the data as a variable:

Document= ({"Name": "ZHF"})

Db.maple.insert (document)

Document Update:

MongoDB uses the update () and Save () methods to update the documents in the collection

Parameter description:

The query:update query condition, similar to that in SQL update query , is behind.

Update:update objects and some updated operators (such as $, $inc ... ) and so on, can also be understood as SQL Update query Inside Set behind the

Upsert: Optional, this parameter means that if there is no Record of update, insert objnew,true as INSERT, default is false , not inserted.

Multi: optional,mongodb defaults to false, updating only the first record found, if this parameter is true, you can find out all the records on a per-condition basis.

Writeconcern: Optional, throws an exception level.

Db.maple.update ({"Name": "ZHF"},{"$set": {"name": "Zhanghongfeng"}})

The operator can also be used to judge the way

> db.maple.update ({"Age": {"$eq": 35}},{' $set ": {" City ":" Chengdu "}})

# Find documents with age equal to and set the city to Chengdu

> db.maple.update ({"City": "Chengdu"},{"$inc": {' Age ': 1}})

# Find documents for Chengdu in the city and Add age 1

> db.maple.update ({"City": "Chengdu"},{"$inc": {' age ':-1}})

# Find documents for Chengdu in the city and subtract age by 1

#unset: Delete a field

> db.maple.update ({"Age": 35},{$unset: {"Programming": 1}})

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

> Db.maple.find ()

{"_id": ObjectId ("5a35d6278ef76f6d57aae92c"), "name": "Zhanghongfeng_maple"}

{"_id": ObjectId ("5a35d7ce8ef76f6d57aae92d"), "age": +, "City": "Chongqing"}

{"_id": ObjectId ("5a35d8548ef76f6d57aae92e"), "favorite": "Basketball"}

{"_id": ObjectId ("5a3611de366b42e0050debd8"), "coding": ["C", "Python", "Go", "Java"]}

$push operation: Append Value To field, field must be array type, if field does not exist, a new array type will be added.

> db.maple.update ({"Age": 35},{$push: {"Programming": "JavaScript"}})

> Db.maple.find ()

{"_id": ObjectId ("5a35d6278ef76f6d57aae92c"), "name": "Zhanghongfeng_maple"}

{"_id": ObjectId ("5a35d7ce8ef76f6d57aae92d"), "age": +, "City": "Chongqing", "Programming": ["JavaScript"]}

{"_id": ObjectId ("5a35d8548ef76f6d57aae92e"), "favorite": "Basketball"}

{"_id": ObjectId ("5a3611de366b42e0050debd8"), "coding": ["C", "Python", "Go", "Java"]}

# An array is added when the array does not exist

> db.maple.update ({"Age": 35},{$push: {"Programming": "MySQL"}})

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

> Db.maple.find ()

{"_id": ObjectId ("5a35d6278ef76f6d57aae92c"), "name": "Zhanghongfeng_maple"}

{"_id": ObjectId ("5a35d7ce8ef76f6d57aae92d"), "age": +, "City": "Chongqing", "Programming": ["JavaScript", "MySQL" ] }

{"_id": ObjectId ("5a35d8548ef76f6d57aae92e"), "favorite": "Basketball"}

{"_id": ObjectId ("5a3611de366b42e0050debd8"), "coding": ["C", "Python", "Go", "Java"]}

# Existing cases will continue to add data to the array

> db.maple.update ({"Age": 35},{$pushAll: {"Programming": ["Object-c", "HTML"]}})

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

> Db.maple.find ()

{"_id": ObjectId ("5a35d6278ef76f6d57aae92c"), "name": "Zhanghongfeng_maple"}

{"_id": ObjectId ("5a35d7ce8ef76f6d57aae92d"), "age": +, "City": "Chongqing", "Programming": ["JavaScript", "MySQL", ["MongoDB", "Linux"], "object-c", "HTML"]}

{"_id": ObjectId ("5a35d8548ef76f6d57aae92e"), "favorite": "Basketball"}

{"_id": ObjectId ("5a3611de366b42e0050debd8"), "coding": ["C", "Python", "Go", "Java"]}

# add multiple data to the array using the Pushall method

#addToSet

Add only when the array does not exist:

> db.maple.update ({"Age": 35},{$addToSet: {"Programming": "MySQL"}})

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

#pop

Delete First and last element

> db.maple.update ({"Age": 35},{$pop: {"Programming": 1}})

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

> db.maple.update ({"Age": 35},{$pop: {"Programming":-1}})

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

#pull: Delete a specific element

> db.maple.update ({"Age": 35},{$pull: {"Programming": "Object-c"}})

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

Document Lookup:

Let's look at the comparison in the relational database:

Db.maple.find ()equivalentselect * from Maple
Db.maple.find ({"Age": 27})equivalentselect * from Maplewhere age= ' 27 '
Db.maple.find ({"Age": +, "name": "Xing"})equivalentselect * from MapleWhere age= ' and name= ' Xing '
Db.maple.find ({},{"name": 1}) select name from Maple,ifname:0It is not displayednameField
Db.maple.find (). Limit (1)equivalentselect * from MapleLimit 1

Db.maple.find (). Sort ({_id:-1}). Limit (1) equals select * from maple order by _id DESC LIMIT 1

Db.maple.find ({"Age": {"$in", [12,34,100]}})equivalentSELECT * fromMaple where age in (12,3,100)
Db.maple.find ({"Age": {"$nin", [12,3,100]}})equivalentSELECT * fromMaple where _id not in (12,3,100)
Db.maple.find ({"$or": [{"Age": 16},{"name": "Xing"}]})equivalentselect * FROM blog where age = + or name = ' xing '
Db.maple.find ({"Id_num": {"$mod": [5,1]}})Take theid_num MoD 5 = 1The fields, such asid_num=1,6,11,16
Db.maple.find ({"Id_num": {"$not": {"$mod": [5,1]}}})Take theid_num MoD 5! = 1fields, such as in addition to theid_num=1,6,11,16all fields, more than regular, are used together.

$exists determine if a field exists

Db.blog.find ({"name": {$exists: true}}); if the element name exists , it returns
Db.blog.find ({"name": {$exists: false}}); if the element name does not exist , it returns

# Query array:

Db.blog.find ({"coding": {"$size": 4}}) coding array with a length of 3 matches the result

Db.blog.find ({"coding": {"$all": ["C", "Python", "Go", "Java"]}}) must have each of the arrays in the fruit to match the result

MongoDB Learning: Document manipulation