A mongo Optimization -- Query stability check

Because an interface is too slow... Try to optimize (/ baldness) Spring data used- mongo:2.1.3 mongo driver: 3.8.2 You can see me First query sentence. Optimization ideas paging Original page query Due to the large amount of data, the query was slow, and it was later found that there was no need to use aggregation at all. With aggregate que ...

Posted by kat_jumper_33 on Tue, 16 Jun 2020 07:39:31 +0200

On Jetpack -- ROOM database

On Jetpack(1) - ViewModelOn Jetpack(2) - LifecyclesOn Jetpack(3) - LiveDataDemo project Although Android carries SQLite, its operation is troublesome, and if it is a large-scale project, it will become confusing and difficult to maintain, unless you design a very good architecture and package. Of cour ...

Posted by Runnion on Tue, 16 Jun 2020 05:22:09 +0200

10-3 B1-5 query customer's order

Find the order status of the customer, which is displayed as: customer ID, company name, order ID, employee ID select customers.CustomerID,customers.CompanyName,orders.OrderID,orders.EmployeeID from customers,orders where orders.CustomerID=customers.CustomerID and orders.ShipCity=customers.City ord ...

Posted by shortysbest on Tue, 16 Jun 2020 04:20:18 +0200

Ten suggestions for Java exception handling

Preface Ten suggestions for Java exception handling, I hope to help you ~ This article has been uploaded to github: https://github.com/whx123/Jav... Public number: A little boy collecting snails First, try not to use e.printStackTrace(), but to use log printing. Counterexamples: try{ // do what you want }catch(Exception e){ e.printStackTr ...

Posted by sheilam on Mon, 15 Jun 2020 18:07:36 +0200

J2EE project instance super detail

J2WEB course design example I found a good article about database query display error: Analysis of mysql coding errors. And then I have a crack free version navicat . extraction code: dv6k catalog Project Name: xixijiaxiang online e-book City Project background: (if I think about it myself, I won ...

Posted by brucensal on Mon, 15 Jun 2020 07:23:16 +0200

Mybatis framework learning delay loading

catalog Delay loading Implement delayed loading Delay loading using allocation Using Collection to delay loading Delay loading It is to load data when it is needed, and not to load data when it is not needed. Lazy loading is also called lazy loading Advantages: query from single table first, ...

Posted by theDog on Sun, 14 Jun 2020 11:24:43 +0200

spring boot series mybatis paging query

Article catalog preface Introducing pagehelper dependency application.yml Medium configuration Add interface Test paging query interface Problem summary application.yml Configuration of pagehelper in preface If you use mybatis to write paging query, it's troublesome. You need to write the select ...

Posted by dicamille on Sun, 14 Jun 2020 09:01:08 +0200

Chapter 5 of "Introduction to Flask": learning Flask Sqlalchemy is enough. Don't write too many

Chapter 5 of "Introduction to Flask": learning Flask Sqlalchemy is enough. Don't write too many According to my personal understanding, database is a tool to store data and the direct relationship between data and data. No matter the complexity or size of the data it stores, it has no ess ...

Posted by parse-error on Sun, 14 Jun 2020 05:53:41 +0200

Summary of knowledge points of Flutter

1. Theme color setting   class MyApp extends StatelessWidget { // This widget is the root of your application. @override Widget build(BuildContext context) { return MaterialApp( debugShowCheckedModeBanner: false, title: 'Flutter Demo',//Available for Android theme: Theme ...

Posted by notepad on Sun, 14 Jun 2020 02:48:02 +0200

The spring boot series integrates MyBatis framework

Add Dependency <!--Add to mysql and mybatis rely on--> <dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> </dependency> <dependency> <groupId>org.mybatis.spring.boot</groupId> <a ...

Posted by Jragon on Sat, 13 Jun 2020 20:59:15 +0200