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INNER JOIN vs LEFT JOIN, clearly explained: INNER JOIN: only customers who placed an order. LEFT JOIN: every customer. No order? The order columns come back NULL. Rule of thumb: if you need "who did NOT do X", start with a LEFT JOIN.

SQL INTERVIEW QUESTION #2 users has 10 rows. 3 of them have email = NULL. SELECT COUNT(*), COUNT(email) FROM users; What two numbers come back? A) 10, 10 B) 10, 7 C) 7, 7 Reply with your answer.

Comment "SQL" and I'll send you the full guide 📘 Your class average says 82. It's really 66 😳 AVG skips NULLs, so the 4 absent students just vanished. ✅ Fix: AVG(COALESCE(score, 0)) The SQL Mastery Guide covers every trap like this: 24 modules, 250+ labs, one Notion

PYTHON QUIZ x = [1, 2, 3] y = x y.append(4) print(x) What does this print? A) [1, 2, 3] B) [1, 2, 3, 4] C) Error Answer in the replies. No running it first.

Stop turning meeting notes into action items by hand. Paste the raw notes into ChatGPT or Claude and add: "List the decisions, the action items with owner and due date, and the open questions. Use only what is in the notes." Then check it in 2 minutes. Done.

WHERE grade = NULL → 0 rows. 🤯 12 students missing… and SQL says nobody? NULL isn't zero or blank. It means UNKNOWN. Fix: use IS NULL ✅ 💬 Comment "SQL" and I'll DM you the full SQL Mastery Guide. 💾 Save this before your next exam or interview.

SQL INTERVIEW QUESTION #1 orders has 100 rows. You run: SELECT o.id, c.name FROM orders o JOIN customers c ON o.customer_id = c.id; You get 130 rows. Nobody added orders. What happened? How do you fix it?

PYTHON STRING METHODS, ONE LINE EACH .strip() - trim spaces at both ends .split(",") - text to list ",".join(items) - list to text .replace("a", "b") - swap text .lower() / .upper() - change case .find("x") - position, or -1 Save this for your next script.

Ep-5 [Run Order] #sql #computerscience #techlover