使用修改器

db.analytics.insert({“url”:”www.example.com”,”pageviews”:20}) WriteResult({ “nInserted” : 1 })

db.analytics.update({“url”:”www.example.com”}, … {“$inc”:{“pageviews”:1}}) WriteResult({ “nMatched” : 1, “nUpserted” : 0, “nModified” : 1 }) db.analytics.find() { “_id” : ObjectId(“5842ac04b7e23e09e7136ada”), “url” : “www.example.com”, “pageviews” : 21 }

db.users.find() { “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”), “relationships” : { “firends” : 32, “enemies” : 2 }, “username” : “joe” } db.users.findOne() { “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”), “relationships” : { “firends” : 32, “enemies” : 2 }, “username” : “joe” } db.users.update({“_id”:ObjectId(“58429e9fb7e23e09e7136ad9”)}, … {“$set”:{“favorite book”:”war and peace”}}) WriteResult({ “nMatched” : 1, “nUpserted” : 0, “nModified” : 1 }) db.users.findOne() { “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”), “relationships” : { “firends” : 32, “enemies” : 2 }, “username” : “joe”, “favorite book” : “war and peace” } db.users.update({“username”:”joe”},) 2016-12-03T19:44:19.433+0800 E QUERY [thread1] SyntaxError: expected expression, got ‘)’ @(shell):1:35

db.users.update({“username”:”joe”}, … {“set”:{“favorite book”:”Green Eggs and Ham”}})    WriteResult({ “nMatched” : 1, “nUpserted” : 0, “nModified” : 1 })    db.uesrs.findOne()    null    db.users.findOne()    {        “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”),        “relationships” : {            “firends” : 32,            “enemies” : 2        },        “username” : “joe”,        “favorite book” : “Green Eggs and Ham”    }    db.users.update({“username”:”joe”},    … {“set”:{“favorite book”:[“cat’s cradle”,”foundation trilogy”,”ender’s game”]}}) WriteResult({ “nMatched” : 1, “nUpserted” : 0, “nModified” : 1 }) db.users.findOne() { “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”), “relationships” : { “firends” : 32, “enemies” : 2 }, “username” : “joe”, “favorite book” : [ “cat’s cradle”, “foundation trilogy”, “ender’s game” ] } db.users.update({“username”:”joe”},{“$unset”:{“favorite book”:1}}) WriteResult({ “nMatched” : 1, “nUpserted” : 0, “nModified” : 1 }) db.users.findOne() { “_id” : ObjectId(“58429e9fb7e23e09e7136ad9”), “relationships” : { “firends” : 32, “enemies” : 2 }, “username” : “joe” }