Update query in MongoDB shell - mongodb

Question

In the shell, my query is:
db.checkin_4e95ae0926abe9ad28000001.update({location_city:"New York"}, {location_country: "FUDGE!"});
However, it doesn't actually update my records. It doesn't error either. When I do a db.checkin_4e95ae0926abe9ad28000001.find({location_city:"New York"}); after running this, I get all my results but the location_country has not changed:
{
"_id": ObjectId("4e970209a0290b70660009e9"),
"addedOn": ISODate("2011-10-13T15:21:45.772Z"),
"location_address1": "",
"location_city": "New York",
"location_country": "United States",
"location_latLong": {
"xLon": -74.007124,
"yLat": 40.71455
},
"location_source": "socialprofile",
"location_state": "New York",
"location_zip": ""
}

Answer 1

This is because in second parameter of update function you need to use $set operator to update location_country as in example below:
db.checkin_4e95ae0926abe9ad28000001.update(
{location_city:"New York"}, //find criteria
// this row contains fix with $set oper
{ $set : { location_country: "FUDGE!"}});
Here you can find a list of available update operators.

Answer 2

Changed in version 3.6.
Following is the syntax for update :
db.collection.update(
<query>,
<update>,
{
upsert: <boolean>,
multi: <boolean>,
writeConcern: <document>,
collation: <document>,
arrayFilters: [ <filterdocument1>, ... ]
}
)
Example :
db.getCollection('products').update({},{$unset: {translate:1, qordoba_translation_version:1}}, {multi: true})
In your example :
db.checkin_4e95ae0926abe9ad28000001.update(
{location_city:"New York"}, //query
// $update query
{ $set : { location_country: "FUDGE!"}});
By default, the update() method updates a single document. Set the Multi Parameter to update all documents that match the query criteria.
Example 2 :
db.checkin_4e95ae0926abe9ad28000001.update(
{location_city:"New York"}, //query
// $update query
{ $set : { location_country: "FUDGE!"}}, {multi: true});

Answer 3

db.m_country.update(
{"countryId": "962a0935-bf3d-4f63-a53c-254760273ede"},
{$set: {'countryPopulation': '12540000'}})

Answer 4

Before Update
> db.student.find({name:"Venky"}).pretty();
{
"_id" : ObjectId("6012e64dc2979ddffe1e5df9"),
"name" : "Venky",
"dept" : "MCA",
"age" : "26",
"phone" : "89786465"
}
Update Command
> db.student.update({name:"Venky"},{$set: {name:"DODDANNA CHAWAN",dept:"MCA(CS)", age:"25", phone:"1234567890"}});
Find Command See Result
> db.student.find({name:"DODDANNA CHAWAN"}).pretty();
After Updated Result
{
"_id" : ObjectId("6012e64dc2979ddffe1e5df9"),
"name" : "DODDANNA CHAWAN",
"dept" : "MCA(CS)",
"age" : "25",
"phone" : "1234567890"
}
in real life use unique "_id" to match the document becuase names will found as duplicates