Common Data Structure Operations and
Array Sorting Algorithms

It could be useful to have it as a cheat sheet

SQL EXECUTION ORDER

SQL Doesn’t Run the Way You Think It Does!

Most people assume SQL runs top to bottom—
but in reality, the database follows a completely different process.

Here’s what actually happens when you hit Run:

🔹 FROM & JOIN – First, SQL figures out where to pull the data from.
🔹 WHERE – Then, it filters out rows that don’t match your conditions.
🔹 GROUP BY – If needed, it groups the remaining rows together.
🔹 HAVING – Now, it filters those groups (not individual rows).
🔹 SELECT – Finally, it picks the columns you asked for.
🔹 ORDER BY – It sorts the result.
🔹 LIMIT – At the very end, it restricts the output.

Why does this matter?
⤷ You can’t use column aliases in WHERE
because SELECT runs later.
⤷ Filtering after grouping (HAVING)
is less efficient than filtering before (WHERE).
⤷ Understanding this helps you write faster, better queries.

Most analysts assume SQL reads queries like English.
✅ But databases have their own logic—and mastering it makes
you a 10x better analyst!

JOB INTERVIEW CHEAT SHEET

What is JSX?

JSX (JavaScript XML) is a special syntax in React that lets you write HTML-like code inside JavaScript. It makes your code more readable and intuitive because you can describe the UI directly in your JavaScript code.

Why is JSX useful?

✅ Easier to write & read – Looks like HTML but works inside JavaScript.
✅ More powerful than HTML – You can use variables, functions, and logic directly inside JSX.
✅ Optimized by React – JSX gets converted into super-efficient JavaScript calls behind the scenes.
Example of JSX in action:

const name = "Borislav";  
const element = <h1>Hello, {name}!</h1>;  

🚀 Here, {name} is a JavaScript variable inside JSX!

JSX is not HTML – it's just syntactic sugar for React.createElement(). You must wrap elements properly (e.g., use one parent tag).

Want to build awesome React apps? JSX is the way to go! 🔥