mongodb query array length

In the four CRUD operations, a record or document is obtained from the collection of mongodb databases. For non-DBAs, query is the most used. Therefore, if you have learned the query, it will be of great help for us to better operate the database in

1. PrefaceIn the previous article, we introduced MongoDB. Now, let's look at how to do a regular crud operation in MongoDB. After all, as a storage system, it is the basic function of the data to be increased and censored operation.The additions and

Inserting more than one test data> for (i=1;i... db.blog.insert ({"title": I, "content": "MongoDB Test article. "," name ":" Liu "+i});... }Db.blog.list.find (). Limit ((). ForEach (function (data) {print ("title:" +data.title);}) Cyclic foreach

Production Environment Best Practices1. Linux:1] disable the atime option of the file system/partitionVI/etc/fstabAdd noatime and nodiratime after the corresponding partition itemLabel =/1/ext3 defaults 1 1Label =/data1/Data ext4 defaults, noatime,

1. find MongoDB uses find for query. The query is to return a subset of the documents in a collection. The range of the child set is from 0 documents to the first parameter of the entire set. find. Determines which documents are to be returned. The

Mongodb entry-8 query 3 continue to learn about mongodb query $ or $ nor $ or, or the meaning is identified as long as there is a match. $ nor is opposite to $ or, as long as $ or can be found as the removed part. [html] db. user. find () {_ id:

In the previous article, we talked about MongoDB installation and management, which involves some concepts, data structures, and some API calls. It doesn't matter if you don't know it. It's actually very simple. This article will briefly introduce

Recently in the study of MongoDB, the article using MongoDB in. NET is either an early driver version or the data is very small, so write an essay to recordThis paper mainly records1. What is MongoDB2.MongoDB installation under WindowsUsing MongoDB

[From: http://like-eagle.iteye.com/blog/850401]   Compared with relational databases, MongoDB has the following advantages:① Weak consistency (eventual consistency) ensures the user access speed:For example, in a traditional relational database, a

Recently in the study of MongoDB, online search found that the use of MongoDB in. NET article is either an early driver version, or very little information, so write an essay record, this article in detail to introduce to you. NET in the use of