Posts

Showing posts with the label constructors

Featured Post

SQL Query: 3 Methods for Calculating Cumulative SUM

Image
SQL provides various constructs for calculating cumulative sums, offering flexibility and efficiency in data analysis. In this article, we explore three distinct SQL queries that facilitate the computation of cumulative sums. Each query leverages different SQL constructs to achieve the desired outcome, catering to diverse analytical needs and preferences. Using Window Functions (e.g., PostgreSQL, SQL Server, Oracle) SELECT id, value, SUM(value) OVER (ORDER BY id) AS cumulative_sum  FROM your_table; This query uses the SUM() window function with the OVER clause to calculate the cumulative sum of the value column ordered by the id column. Using Subqueries (e.g., MySQL, SQLite): SELECT t1.id, t1.value, SUM(t2.value) AS cumulative_sum FROM your_table t1 JOIN your_table t2 ON t1.id >= t2.id GROUP BY t1.id, t1.value ORDER BY t1.id; This query uses a self-join to calculate the cumulative sum. It joins the table with itself, matching rows where the id in the first table is greater than or

All About Init and Delete Constructors Python

Image
Python class has two constructors. One is the init, and the other one is del. Why do you need these two and their real purpose explained? The initialization method is called __init__ while the finalization or destructor method is called __del__. Python methods with a double underscore character are for internal (not intended for direct access by the outside world) use. There are no true private methods in Python classes, but convention says that a method that begins with a single underscore is considered private, and a double underscore indicates it is internal (only to be used by the system.) Python Constructors  Init Constructor object.__init__(self[, ...]) Called after the instance has been created (by  __new__() ), but before it is returned to the caller. The arguments are those passed to the class constructor expression.  If a base class has an  __init__()  method, the derived class’s  __init__()  method, if any, must explicitly call it to ensure proper initialization of the base