I made a one-page SQL cheat sheet that covers every command a beginner needs. Here's a preview of what's on it:

SELECT & Filter

SELECT column1, column2 FROM table WHERE condition;
SELECT DISTINCT column FROM table;
SELECT * FROM table WHERE column LIKE '%pattern%';
SELECT * FROM table WHERE column IN ('val1', 'val2');
SELECT * FROM table WHERE column BETWEEN 10 AND 50;

Aggregations

SELECT COUNT(*), AVG(salary), SUM(revenue)
FROM table
GROUP BY department
HAVING COUNT(*) > 5;

JOINs

-- INNER: only matching rows
SELECT * FROM orders o INNER JOIN customers c ON o.customer_id = c.id;

-- LEFT: all rows from left table + matches
SELECT * FROM customers c LEFT JOIN orders o ON c.id = o.customer_id;

Subqueries & CTEs

-- CTE for readability
WITH top_earners AS (
  SELECT name, salary, RANK() OVER (ORDER BY salary DESC) as rnk
  FROM employees
)
SELECT * FROM top_earners WHERE rnk <= 10;

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That's about 30% of the full cheat sheet. The complete version covers window functions, CASE statements, date functions, string manipulation, indexing tips, and more — all on one printable page.

It's included free in the ProEdge SQL Bundle along with:

• 📘 Full beginner-to-job-ready SQL guide

• 🗂️ 3 practice datasets

• ✅ Exercise answer key
  

• 💼 20 interview questions with answers

• 🚀 Quick-start action plan

Start your 7-day free trial — access the full bundle instantly, cancel anytime → whop.com/proedge-academy/

Use code LAUNCH for 25% off when your trial converts.

I've been reviewing SQL interview rounds from companies hiring junior data analysts and backend devs. The same 20 questions keep showing up — and most career switchers bomb them because they studied syntax, not problem-solving.

Here are 5 of the 20 to test yourself:

1. What's the difference between WHERE and HAVING?

Most people say "HAVING is for groups." That's technically right but misses why interviewers ask it. They want to know if you understand the SQL execution order.

2. Write a query to find the second-highest salary in a table.

If your first instinct is a subquery, you'll pass. If you use DENSE_RANK(), you'll impress. Know both.

3. How would you find duplicate rows in a table?

GROUP BY + HAVING COUNT(*) > 1 is the baseline answer. Bonus points if you mention CTEs for readability.

4. Explain the difference between INNER JOIN, LEFT JOIN, and FULL OUTER JOIN.

Draw a Venn diagram in your head. Interviewers love candidates who can explain joins visually.

5. A table has 1 million rows. Your query takes 45 seconds. How do you optimize it?

This is where most self-taught people freeze. Think: indexes, query plan, avoiding SELECT *.

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The other 15 questions (with full worked-out answers, edge cases, and what interviewers are really testing for) are in the SQL Interview Question Bank — part of the ProEdge Skill Guides bundle.

The bundle also includes:

• 📘 Complete SQL guide (zero to job-ready)

• 📋 One-page SQL cheat sheet

• 🗂️ 3 practice datasets with walkthroughs

• ✅ Full exercise answer key

• 🚀 Quick-start checklist

Start your 7-day free trial — full access to the entire bundle, cancel anytime → whop.com/proedge-academy/

Use code LAUNCH for 25% off when your trial converts.