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SQL Query: 3 Methods for Calculating Cumulative SUM

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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

Python Syntax Errors Cheat Sheet

Here's is the Python syntax errors cheat sheet. In Python, you can avoid errors, if you know syntax rules. These are missing semicolons, adding extra commas, and extra spaces. Further Python is case sensitive. So using the wrong identifier also will give error.

Python syntax cheat sheet


Python Syntax Errors Cheat Sheet

Indentation is unique to Python. You cannot find strict indentation in any other programming language. You need to focus on the three areas while writing a Python program. To avoid errors you need to learn indentation rules.

  • Indentation or Syntax Errors
  • Exceptions
  • Handling Exceptions

1: Indentation

If you do not follow the proper order, you will get an error. The details of one block shroud follow in one vertical line.

The sub-block should be inside of that. In if loop, the IF, ELIF, and ELSE should have the same indentation. Not only, but the statement inside of them should also have the same indentation.

Best Examples

Understand these examples a good material on indentation for you.

2: Exceptions


Python raises an exception, when it encounters an error. These are called system errors.

Python has many built-in exceptions. One best example is ZeroDivisionError

More exceptions all list in one place.

3: Handling Exceptions


To handle exception you need two blocks which are Try and Except. Try Block is the block where you can give your code. Except is the Block where your exception message comes here.

Python Syntax Example:

try:
d = int(20)
f = str
g = d + f
except TypeError:
  print('This is TypeError Exception')
else :
  print('No exception happened')

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