mongodb count example

SummaryThe previous article introduced CRUD operations, which will basically do a lot of work. However, if you encounter the operation of statistical classes, then you need to learn the contents of this article.Related articlesGetting started with [MongoDB][MongoDB] additions and deletions changeCount,gourp,distinct,mapreduceCountFunctions like the Count function

Let's say we have a MongoDB collection, Take this simple set as an example, we need to include how many different mobile phone numbers in the collection, the first thought is to use the DISTINCT keyword, Db.tokencaller.distinct (' Caller '). length If you want to see specific and different phone numbers, then you can omit the length property, since Db.tokencaller.distinct (' Caller ') returns an array of

() { return phoneno; } public void Setphoneno (String phoneno) { This.phoneno = Phoneno; } public int getId () { return ID; } public void setId (int id) { this.id = ID; } } 4, the entity class into MongoDB, and then according to the conditions obtained: @Autowired mongotemplate mongotemplate; @Test public void Mongosavegettest () throws jsonprocessingexception { String dbName = Mongotemplate.getdb (). GetName (); Logger.inf

Large SkipWhen paging the data, it is generally necessary to skip how many records and limit how many records, such as in MySQL: SELECT * from large_table ORDER by ' id ' LIMIT 10000, 30 This process is slow because the database needs to be scanned from the first record to the 10,000th record, which is time consuming. In http://idning.github.io/point-large-skip.html, the above SQL code summarizes two optimization methods: Method 1: Select t.*from ( select ID from large_ta

This article introduced the MongoDB in the MapReduce implementation of data aggregation method, we mentioned MongoDB in the data aggregation operation of a way--mapreduce, but in most of the day-to-day use of the process, We do not need to use MapReduce to do the operation. In this article, we simply talk about the implementation of the data aggregation operation with the aggregation function. In addition

Tags: blog io os file on log CTI BS AD#count CollectionDb.news.count ({"Lpublishtime": {"$gte": 1358697600000}});#mongo导出Mongoexport-h 192.168.1.175--port 33000-d booaa_so-c weibo-f ' _id '-Q ' {\ ' lweibotime\ ': {\ "\ $gte \": 1349020800000,\ "\ $l T\ ": 1351699200000}}"-O Weibo_20121201_33000.ids ##################### #20121227. txt#######################mongo导出0.1Mongoexport--port 33000-d booaa_so-c bbs-f ' _id '-o 33000.bbs.ids;#替换, replace the e

Label:Let's say we have a MongoDB collection, take this simple set as an example, we need to include how many different mobile phone numbers in the collection, the first thought is to use the DISTINCT keyword, db.tokencaller.distinct (' Caller '). Length If you want to see specific and different phone numbers, then you can omit the length property, since db.tokencaller.distinct (' Caller ') returns an a

In the project, we need to download the number of files, users download the file every time, the corresponding download times plus 1, similar applications in many download stations. This article unifies the example to use the Php+mysql+jquery, realizes the click File, downloads the file, the number of cumulative process, the whole process is very smooth. Preparatory work This example needs the reader to

The example in this article describes the process usage of the thinkphp progress Count class. Share to everyone for your reference. Specifically as follows: There is a requirement in the project to limit the number of processes because a background task compares bandwidth. Spent a bit of time, wrote the class, the current version of the function is relatively simple. Process.class.php files are as follows

In the previous article, we talked about MongoDB's command to get started, this blog will be based on the previous blog created database and table completed a simple Java MongoDB CRUD Example, using Java to connect MongoDB database. and implement routines such as creating a database, getting a table, traversing objects in a table, and CRUD operations on objects i

the previous large list of errors or people looking uncomfortable, we want to destroy them.Error:cannot Find module '. /build/release/bson ' Solution{[Error:cannot find module '. /build/release/bson '] Code: ' Module_not_found ' }js-bson:failed to load C + + Bson extension, using pure JS versionThe first two lines say that no Bson module was found. Okay, we'll install it right away:NPM Install BsonThen the Bson in D:\nodejsdemo\node_modules\mongodb\n

In the previous article we talked about MongoDB's command to get started, this blog will be based on the database and table established in the previous blog to complete a simple Java MongoDB CRUD Example, the use of Java to connect MongoDB database, and the implementation of database creation, get the table, Routines such as traversing objects in a table, CRUD op

database will be stored on different shard;--A collection is still stored on the same shard, to make a single collection also Shard, but also need to do some operations on the collection alone;--the collection system of shards automatically creates an index (which can also be created in advance by the user);--the collection of a shard can have only one unique index on the Shard key, and other unique indexes are not allowedFour, Test and summaryUse the for (i=1;iProblems encountered during deplo