find aggregate mongodb

: "Dgreenthumb", Helpful_ Votes:3, voter_ids:[ {new ObjectId ("59884b76b53fab2a8024b600")}, {new ObjectId (" 59884b76b53fab2a8024b601 ")}, {new ObjectId (" 59884b76b53fab2a8024b602 ")} }In the evaluation information above, because MongoDB does not support junction queries, redundancy stores user_name and a voter_ids array to store the users who vote on the comment. It removes duplicate votes and also gives us the ability to query all comments that a u

Create a databasePerforming an operation into MongoDB using parameter mode can also be verified using Db.auth ().[Email protected]:/usr/local/apache243/htdocs# /usr/local/mongodb/mongo -uroot-pxxxxx localhost : 27017/adminThe following is the first time a new database is created Use demoswitched to db DEMO> Db.user.insert ({name: "Zhaoxingzhuang", Age:18,sex: "Man", Location:{province: " Shandong ", City:

We have implemented a limited fix for MongoDB2.2 and 2.4 limited fixes in version 2.2. The following query statement will work as you wish and return the result within milliseconds: db. posts. find ({userId :{$ in: [12, 24, 56,…]}). Sort ({date:-1}). limit (-100) So you may have thought this was perfect ...... Unfortunately MongoDB 2.2 and 2.4 limited fixes 2.2. The following query statement returns the res

Label:.projectfilelogerrodown $set find divload Db.project.find ({content: ', es_update: ' No ', New_import: ' 1 '});Db.project.distinct (' Wj_source_type ');Db.project.find ({Source: ' TPM ', New_import: ' 1 ', file_id:{$nin: [', ' is_download ', ' download_error ', ' file_size_ Error ', ' Upload_failure ']},wj_yuangao_id:{$ne: '}})Db.project.update ({Source: ' TPM ', New_import: ' 1 '},{$set: {file_id: ', es_update: ' No ', content: '}},false,true

1. Specify the key to returnDb. [Documentname].find ({condition},{key specified})Data Preparation Persons.jsonvar persons = [{Name: "Jim",age:25,Email: "[email protected]",c:89,m:96,e:87,Country: "USA",books:["JS", "C + +", "ExtJS", "MONGODB"]},{name: "Tom",age:25,Email: "[email protected]",c:75,m:66,e:97,Country: "USA",books:["PHP", "JAVA", "ExtJS", "C + +"]},{Name: "Lili",age:26,Email: "[email protected]"

]"}, Tags: ["Coding","Database"], pubdata:new Date}Cmd://INSERT into the posts collectionDb.posts.insert ({title:"My First blog post", author:{firstName:"YY", LastName:"KK", Email:"[email protected]"}, Tags: ["Coding","Database"], pubdata:new Date});Note: _id should be unique.Find:// get the oldest inserted data Db.posts.findOne (); // getall the data db.posts. Find ();Db.posts. Find // count the amountDb.p

are unordered in order to get an ordered document that requires the Sort function syntax:db.account.find (). Sort ({age:-1}) in descending order of age The return value of the Find function is a cursor object, and the sort function is provided by the cursor object, and the Find function query does not return all legitimate documents at once for the first time to return 101 or 200M of data and cache it to m

Tags: http color io java ar div sp CTI onA. New date () and date () are not the same thing, refer toHttp://stackoverflow.com/questions/3505693/difference-between-datedatestring-and-new-datedatestringIf you want to get the number of milliseconds since the epoch, you must use the new Date ().The date () appears to be just a function that returns a string. It is easy to confuse the concept of man with no significant effect.B. The Date object provides a gettime ()2. In a query statement, you can use