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Lesson 5 Basic _ multi-table query 1. Multi-table relations In project development, when designing database table structure, the table structure will be analyzed and designed according to the business requirements and the relationship between business modules. Because business is related to each other, there are also various connections among ...

stay Access Guide: An article about Huawei Account Services We have described the advantages of Huawei Account Services, such as one-click authorization to log in to Huawei for sharing the whole scene, sharing all user resources of Huawei Account, account security, reliability, easy and fast access, and why it can help developers to increase th ...

1, In Vue3, the difference between the use of rouyou and Vue2 First, if you habitually use this$ Router, you will definitely get an error report, because Vue3 does not have this and uses a new API, so we need to introduce the function useRouter in router at this time import { defineComponent, reactive} from "vue" import { useRouter } from "vu ...

Problem description First read enterprise_ of_ English_ Peter Brown, refer to the above article to calculate the average information entropy of Chinese. Database: https://share.weiyun.com/5zGPyJX Experimental principle Information entropy The concept of information entropy was first proposed by Shannon (1916-2001) in 1948 based on the c ...

1, View View is a virtual table (non real). Its essence is to obtain a dynamic data set according to SQL statements and name it. When using, users only need to use the name to obtain the result set, which can be used as a table. Using the view, we can pick out the temporary table in the query process and implement it with the view. In t ...

Based on Multipass In Catalina and later versions, MacOS no longer supports 32-bit software, so installing iraf / piraf on Mac cannot open xgterm. The best way I've found so far is to use Multipass (a lightweight ubuntu virtual machine) to install iraf Multipass installation & basic commands Enter command: sudo snap install multipas ...

proxy pattern Simply put: instead of accessing the real object, the proxy object can be used to provide additional functional operations to extend the function of the target object without modifying the original target object. The main purpose of the proxy mode is to extend the capabilities of the target object, for example, you can add s ...

If you don't say much, see the effect first Below is the effect of not wearing a mask (cover it with an idol first) Here is the effect of wearing a mask Let's describe this effect again. In fact, it's not a picture, but read by the camera in real time. First of all, thank AIZOOTech's open source project - FaceMaskDetection. At the same time, ...

Relationship among process, thread and co process Process: in essence, it is an independently executed program. Process is the basic concept of resource allocation and scheduling by the operating system. The operating system is an independent unit for resource allocation and scheduling.Thread: it is the smallest unit that the operating system ...

I'm Zero, not to say a lot, Brain Map Brain Map Combing As long as you follow Flutter, this article is definitely useful==>Highly recommended ➕ Collection Introduction to Multi-Channel Packaging The main role of multi-channel packaging is to meet the operational needs of products, statistical channels and activity results.Previ ...