Tag：Group
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Time：2021-6-3
Today, let’s summarize the usage of group by with examples. To sum up: group by: all, cube, rollup, compute, compute by Create data script Create Table SalesInfo (Ctiy nvarchar(50), OrderDate datetime, OrderID int ) insert into SalesInfoSelect n ‘Beijing’, ‘2014-06-09’, 1001 union allSelect n ‘Beijing’, ‘2014-08-09’, 1002 union allSelect n ‘Beijing’, ‘2013-10-09’, 1009 union allSelect […]
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Time：2021-5-12
preface Following the previous pure front-end simulation of the telegram chat systemAfter that, I decided to add back-end functions. This time, I considered using a more concise interface and a more elegant implementation to refactor the UI interface. The main technology stack is vue2 + mongodb + koa2. The project should have been completed and […]
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Time：2021-5-8
1、 Introduction to Linux group In Linux, each user must belong to a group, not independent of the group. In Linux, each file has the concept of owner, group and other groups 1) Owner 2) Group 3) Other groups 4) Change the user’s group 2、 File / directory owner Generally, it is the creator of […]
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Time：2021-4-23
The third-party cookie technology can make the browser mark a clearer user portrait, and create a better condition for the network commercial advertising. As one of the largest companies in the world, Google’s cookie technology is closely related to its business model based on advertising revenue. However, in the face of the rise of users’ […]
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Time：2021-3-4
Task queueP133 By putting the relevant information of the task to be executed into the queue, and then processing the queue, you can delay the execution of those time-consuming operations. This method of handing the work to the task processor for execution is called task queue.P133 FIFO queueP133 sureRedisTo store the information about the task, […]
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Time：2021-2-27
Additional functions of “local characteristics” Due to historical factors, Django brought his owndjango.contrib.localflavor–A variety of code snippets that can be used in a particular country, region, or culture. To facilitate maintenance and reduce the size of the Django code base, the code is now released separately from Django. See the official document for details: https://django-localflavor.readthedocs.org/ […]
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Time：2021-2-12
Perhaps most netizens still don’t know how to deal with the problem of win7 system Baidu cloud quitting from the group. Although the steps of win7 system Baidu cloud quitting from the group are not difficult, some friends still don’t know how to solve it, so I collected a few solutions for win7 system Baidu […]
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Time：2021-2-11
Preface series__ >>> [graffiti footprint of Internet of things] interface description of graffiti cloud platform Our series of articles will focus on how to complete the development of an intelligent “airtight kissing machine”. Hope to help the long-distance relationship__ or__ Foreign lovers! In this article, we will explain the API interface list~ Interface list and […]
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Time：2021-2-8
I have collected and sorted out the daily commonly used linux system commands for your reference only. If you feel that the article is not very convenient, brother migrant workers has also sorted out the commands in this article into PDF. You can refer to the way at the end of the article to get […]
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Time：2021-2-7
Difficult to understand the “female consumer psychology” has become a major challenge for related businesses.Women’s clothing industry has been facing the risk of uncertainty, that is, the clothing designed and produced from the perspective of enterprises can not catch up with the changes of consumer demand. “2020 China’s clothing industry data Zhongtai Research Report” mentioned […]
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Time：2021-2-6
Delete library and runI often hear about it. However, it can only be a topic of ridicule. I can’t do it in real work. Otherwise, the library will be deleted and I’m afraid I can’t run away. So, backup is very important!!!!! Tar command Copy (local)backupsThe whole system, later restore or restore to this machine) […]
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Time：2021-1-30
There are two ways to create users under LinuxadduseranduseraddTheir differences and main usages are as follows: adduser The usage of addUser is very simple. You only need toadduser+usernameIt is as follows: sudo adduser alvin This command is actually a Perl script, and its underlying layer is calling the useradd command. Many online tutorials say that […]
