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There are many attributes of fields in MySQL, and the impact on performance can be large or small, so it's necessary to explore the attributes. 1, NULL / NOT NULL For external programs, NULL is an unknown, imprecise, and indescribable value. Therefore, it is clearly stipulated in the development specifications of many companies that it must be ...

Published in the vn.py community official account [vnpy-community] Original author: the first quarter of the moon 𞓜 release time: March 20, 2020 With the increasing popularity of quantitative trading in the domestic financial market, the competition between CTA strategies has become more and more fierce. In addition to the core transacti ...

Page application needs Vuex to manage the state of global / module. If large single page components rely on events / props to communicate values, they will be coupled together. because This requires unified management of Vuex. Of course, for a small single page application, reference to Vuex will increase the complexity. Therefore, it ...

Get a framework, in addition to understanding the framework, but also to achieve the basic CURD operation. Add to 1. Configure route, specify add page; // Add the following in routes/web.php: // Add page and storage path Laravel7/resources/views/Users/add.blade.php // The view file ends with. blade.php by default Route::get('/add', function(){ ...

Have you ever encountered such a situation: the response of the web page is very slow, you find no response after submitting a form, and then you click the submit button crazily (12306 is often so angry). If you have done anti duplicate submission, it's OK, otherwise it's a disaster of what level... This paper mainly uses custom annotation, sp ...

Table of contents Preface Custom parameters Log output mode file network transmission data base Scientific use Reference documents   Preface A year ago, I wrote an introduction to NLog NLog log framework use inquiry-1 , this article briefly introduces the basic use of NLog and ho ...

abstract stay Last article In, we talked about how to implement an Http server in Golang.But in the end, we can find that although DefaultServeMux can do routing distribution, its function is also imperfect. Routing distribution by DefaultServeMux is not a RESTful style API, and we cannot define the method required for requests or add query p ...

1. Priority of message If there is a requirement now, we need to push some of the highest priority notifications to the client. We can use the sortedset of redis or the message priority attribute of rabbit we are going to talk about today Producer code using RabbitMQ.Client; using System; using System.Collections.Generic; using System. ...

WPF Native binding and command Function Guide Wei Liuhong February 21, 2020 Now, when it comes to WPF It seems that we have forgotten how to use WPF without MVVM, framework (such as Prism) and so on. Of course, we don't use the framework and MVVM here. We don't use WPF as we use Winform. Instead, we need to go back to the source and re recogn ...

1. Learn to use ndarray 1.1 What is ndarray? ndarray is a multidimensional array object in NumPy that can be one-dimensional, two-dimensional, or even more.Of course, creating more dimensional arrays is not his advantage. Its advantage is that it has a rich method of operation, and it is also the base of another advanced Python library, panda ...