MongoDB MongoDB3.x 4.0 1. First of all, run the test directory under the mongod-- dbpath c: test C disk through cmd. After running, there are a large number of files in the c:test directory. According to the saying, the startup data at this time 2....
do you want to query the number of records in a collection that are not duplicated by deptId? the instruction db.model.distinct on the mongodb command line ( "deptId "). Length can be implemented, but it can t be used in node. How do you use it in no...
the background of the project is to send data to the three-party platform. To ensure that the data can be traced back, the messages (Json format string) under the three-party platform are stored under the Message.bizData node, as shown in the following ...
koa connects to mongodb database time error Unexpected token import, has been introduced into babel server.js const db = require( . mongodb db ); const Koa = require( koa ); const webpack = require( webpack ); const merge = require( webpack-m...
recently, Ali Yun has been engaged in activities to buy a server, but I don t know much about the server, and I don t know what to say about their configuration. Now I would like to talk about my needs. I hope the eldest brother who knows how to do it ...
question: why is the node.js seen on the Internet used to manipulate databases are generally non-relational databases, relational databases (mysql) is rare? ...
currently uses TP5.0 s framework. Since there is a large form with more than 30 fields in the background, do you have to write a field dictionary first, and then judge that Filter has dropped the extra fields (for example, someone else may submit a fi...
The mongodb query statement can be executed in the visualization software and converted into an php array to report an error. figure 1 shows the result of execution in the visualization software. php: php if you have the help of a great god, you ca...
use _ id as the query condition in pymongo . ...
in this diagram, it is a composite retrieval of multiple conditions, and the crux of the problem is that any condition in it can be combined at will. It may be three conditions, it may be five conditions, and the possible three conditions may be diff...
what is described in the book is that each process is allowed to have a maximum of 2563 (16,777,216) different ObjectId in the same second. The maximum 24-bit random number is 16777216, but why is it in parentheses, and how is 2563 calculated outside par...
index = self.xiaoMiQuanCollection.createIndex ({ "unique_charcter ": 1, "name ": hashed }, { "unique ": True}) res = self.xiaoMiQuanCollection.find (index) TypeError: Collection object is not callable. If you meant to call the createIndex ...
there are two record: entries as follows query condition is type=gz--> detai is a List, there is an obj, query condition in this obj, and this filed is a List, depending on whether the value in it conforms to . query the entire document of all type ...
{ "_id" : ObjectId("5bd6c4f3c3474d25ef31e224"), "unique_charcter" : [ "FqT9lRq7wdoSqjbfvQALU7mf4R0M" ], "name" : "-_2017-2018.3-14.pdf" } { "_id" : ObjectId("5bd6c4f3c3474d25ef31e...
[ { _id:001 ... arrs:[{name: a ,score:10}, {name: b ,score:11}, {name: c ,score:12}, {name: d ,score:13} ] } { _id:002 ... arrs:[{name: a ,score:11}, {name: b ,score:12}, {name: c ,score:13}, {name: ...
topic description the following is a set of built replicas, where 12 nodes are arbitration nodes 192.168.1.10 br 27017 192.168.1.11 purl 27017 192.168.1.12 purl 27017 replica set set is: sss nodejs uses mongoose middleware to connect to mongodb...
problem description Server environment: system: ubunt16 configuration: 16core 64GB memory disk information: logical volume 9.3T ordinary disk mongodb version: 3.6.1 mongodb data volume: 2.4T < H2 > mongodb configuration information: < H2 > fork=...
now the condition is that a List, such as type [ "sh ", "th "] is not the full value in the database type, but only has a prefix . according to this query, the following database shows that type contains sh and th prefixes, and the whole document...
how to effectively get the current timestamp ...
when using MongoRepository, I found that I want to update a field, but MongoRepository only provides the save method, but the save method requires a primary key. I directly use the default _ id as the primary key, and use the save method to insert a piec...
const arr=[ {id:1,name: a }, {id:2,name: b }, {id:3,name: c } ] how can I easily judge whether id exists in arr or not? ...
want to implement a function of dragging and dynamically changing columns now that drag and drop is implemented in draggable, the array of header columns will change as you drag. but the phenomenon is that the columns of table do not change with each...
online project, two customers often have js errors when browsing, and it is found remotely that there is a js file that has been tampered with at random. 1, a customer is from Shaoxing, and this problem can occur in IE browsers. A customer is from Wuh...
I can run before packaging without any error reports. This problem occurs after packaging. reports such an error in the browser, using scaffolding made by create-react-app, and the back end is Node.js, backend. No error is reported: packages two diff...
is currently getting started learning about FFmpeg. When introducing SDL threads, there are the following problems: 1. Create demux_ thread in main thread 2. demux_thread 3. main 4. Complete code ffplay.c -sharpinclude <stdio.h> -sha...