Most useful websites for everyone

 M<ost useful websites for everyone


Comments

Post a Comment

Popular posts from this blog

SQLAlchemy Model.query cheat-sheet

Image
SQLAlchemy  Model  query-cheat-sheet Query Methods Here are some useful query methods to get to know.  - Select records all() MyModel.query.all() Fetches all records from a table. Returns list of objects. first() MyModel.query.first() Fetches just the first result. Returns object or None. - Filtering filter_by() MyModel.query.filter_by(attr='some value') Similar to SELECT * from ... WHERE filter() Examples: MyModel.query.filter(MyOtherModel.some_attr='some value') OrderItem.query.filter(Product.id=3) Similar to filter_by , but instead, you specify attributes on a given Model.-- -- equals: query.filter(User.name == 'ed') -- not equals: query.filter(User.name != 'ed') LIKE : query.filter(User.name.like('%ed%')) ILIKE (case-insensitive LIKE): query.filter(User.name.ilike('%ed%')) IN: query.filter(User.name.in_(['ed', 'wendy', 'jack'])) NOT IN: query.filter(~User.name.in_(['ed', 'wendy', 'jack...
Read more

SQLAlchemy library for python

Image
 SQLAlchemy library for python  Introduction: What is SQLAlchemy? SQLAlchemy is a popular SQL toolkit and Object Relational Mapper.  It is written in Python and gives full power and flexibility of SQL to an application developer.  It is open-source and cross-platform software released under MIT license.  SQLAlchemy is famous for its object-relational mapper (ORM), using which classes can be mapped to the database, thereby allowing the object model and database schema to develop in a cleanly decoupled way from the beginning. It is one type of ORM library, AKA an Object-Relational Mapping library, which provides an interface for using object-oriented programming to interact with a database. Other ORM libraries that exist across other languages include popular choices like javascript libraries Sequelize and Bookshelf. js for NodeJS applications, the ruby library ActiveRecord, which is used inside Ruby on Rails, and CakePHP for applications written on PHP, amongst m...
Read more

Python-Cheat-Sheet

Image
Python-Cheat-Sheet Variables We use variables to temporarily store data in the computer’s memory. price = 10 rating = 4.9 course_name = ‘Python for Beginners’ is_published = True In the above example, • price is an integer (a whole number without a decimal point) • rating is a float (a number with a decimal point) • course_name is a string (a sequence of characters) • i s_published is a boolean. Boolean values can be True or False. Comments We use comments to add notes to our code. Good comments explain the hows and whys, not what the code does. That should be reflected in the code itself. Use comments to add reminders to yourself or other developers, or also explain your assumptions and the reasons you’ve written code in a certain way. # This is a comment and it won’t get executed. # Our comments can be multiple lines. Receiving Input We can receive input from the user by calling the input() function. birth_year  =  i nt(input(‘Birth year: ‘)) The input() function always r...
Read more