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  Django ORM multi table operation (Advanced)   1, Create model Next, we design the corresponding relationship between each table through the book management system. Through the relationship above, we can define our model class. from django.db import models class Book(models.Model): title = models.CharField(max_length= ...

Application and summary of CRC32Mpeg2 implemented by python At present, there are two kinds of Crc calculation methods: Crc32 and CRC32Mpeg2. CRC error detection technology of cyclic redundancy test can prove that the data is complete and error free (it is only very similar to think that it is error free). The methods to ensure reliable data t ...

Last time we added an add? Layer function, this time we will create a neural network to predict / fit the corresponding data. Let's create the following virtual data, which is conic data, but at the same time, some noise is added, and the image is: The corresponding code to create these forged data is: import numpy as np # Create a column (equi ...

XPath (XML Path Language) is a language for finding information in XML documents, which can be used to traverse elements and attributes in XML documents. lxml Is an HTML/XML parser, the main function is how to parse and extract HTML/XML data. lxml, like regular, also uses C is a high-performance Python HTML/XML parser. We can use the XPa ...

Data Acquisition for Public Comments - Basic Version Popular Reviews is a third-party food-related review website that is very popular with the general public. Therefore, the site's data is also very valuable.Preferential offers, number of evaluations, positive reviews and other data are also very popular with data companies. Today I wrote a s ...

In winter vacation, I learned Python by myself because of the boredom of epidemic situation. I started with a few lessons at random All the big guys in the group are learning c + +. I have finished reading the java book, My notebook  (Web view )I don't know if I can open it. python has many libraries with simple syntax, and then learns some sel ...

With the background of blog, we used Pyqt5 to implement a simple calculator. I think it's important to use the eval function of py When did I write the player or implement the java directory tree or xml parser I want to write recently The idea is to click the button and add it to string to form algorithm expression, and then rely on python's po ...

Python because of the simplicity of the language, let's write code in the way of human thinking, it's easier for the novice to start, and the old bird can't let go. To write python (elegant, authentic and neat) code, and to observe the big bull code more often, there are many excellent source codes on Github that are worth reading, such as req ...

python3 environment construction under Linux What are the ways to install Linux software? The manual installation of rpm package rejects this mode, and the dependency needs to be resolved manually yum automatic installation is very easy to handle dependency automatically Source code compilation and installation, more customizable functio ...

Introduction Refer to the following article for the problem of Django2 connecting to MySQL and the solution of modifying the source code: The interaction between Django and MySQL However, there are many problems when the above source code modification method is used in the production environment. This article explains in detail how to solve thi ...