asyncfunctiongetUserActivities(){constresults=awaitActivity.aggregate([{$sort:{userId:1,activityTime:1}},{$group:{_id:"$userId",firstValue:{$first:"$value"},lastValue:{$last:"$value"}}}]);console.log(results);}getUserActivities(); 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12...
When an index covers a query, the explain result has an IXSCAN stage that is not a descendant of a FETCH stage, and in the executionStats, the totalDocsExamined is 0. Query : db.getCollection('qaa').find({roll_no : {$gte : 0}},{_id : 0, roll_no : 1}) Index ...
The documents inserted first will be displayed first. Use the cursor.sort() Method to Get the Last N Records From Most Recent to Less Recent Inserted Documents or Vice Versa Example Code (Last In First Out): > db.stock.find().sort({_id:-1}).limit(3); OUTPUT: { "_id" : Object...
Function<T, R> mapper, Integer pageSize, Integer pageNum, String lastId) { //分页逻辑 long total = mongoTemplate.count(query, entityClass); final Integer pages = (int) Math.ceil(total / (double) pageSize); if (pageNum <= 0 || pageNum > pages) { pageNum = FIRST_PAGE_NUM; } f...
method: [FunctionName("Restaurants")] public static async Task Run([HttpTrigger(AuthorizationLevel.Anonymous, "get", "post", Route = null)]HttpRequestMessage req, TraceWriter log) First, note the FunctionName attribute that determines your function url (so use caution if you want to update ...
1. NoSQL Injection The first rule of secure web development is: Never trust user input. This brings me to the first common misconception: MongoDB doesn’t use SQL, so I don’t have to worry about SQL injection. I’ve spoken with countless developers who have this false sense of security...
Each record: UserID1, UserID2 Separate records: UserID, first_name,last_name, age, gender,... Task: Find all friends of friends of friends of ... friends of a given user. Wikipedia 页面 : Large collection of documents Combination of structured and unstructured data Task: Retrieve all pa...
records: {$slice: ['$records',1]} }, }, { "$unwind": "$records" }, { "$replaceRoot": { "newRoot": "$records" }, } ]); 对某一列的sum db.getCollection("LogSiteStatistics").aggregate([ {"$match":{"SiteName":"开发WebAPI"}}, ...
'text': 'My first blog post!'} 八、通过ObjectId查询 也可以通过它的_id找到一个帖子(post),下面的示例子中演示如何根据给定的一个ObjectId查询数据: #!/usr/bin/python3#coding=utf-8importdatetimeimportpprintfrompymongoimportMongoClientclient=MongoClient()db=client.pythondbpost={"_id":100,"author"...
一、查询类 1. 字符串类型 1.1 $strLenCP - 计算字符串的长度 1.2 $substrCP - 字符串截断 pipeline中使用 1.3 $split - ...