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Learn how to build a custom Typora theme from scratch with this beginner-friendly guide. Customize colors, fonts, and layouts to create your perfect writing environment.

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Learn the critical difference between INNER JOIN and LEFT JOIN in SQL. This beginner-friendly guide shows you how to prevent data loss with clear examples using customer and order data. Discover when to use each join type to get accurate results.

Stop Losing Data in SQL: When to Use LEFT JOIN vs INNER JOIN (With Visual Examples)

Learn SQL joins from scratch with real customer and order examples. This beginner-friendly guide covers INNER, LEFT, RIGHT joins and how to combine data from multiple tables with practical queries you can try today.

SQL Joins Explained: A Beginner's Guide with Real Customer Data Examples

My 3-week journey from SQL beginner to writing 4-table joins. A step-by-step learning path with 50 practice exercises that took me from zero to confidently querying multiple tables.

From Zero to Joining 4 Tables: My SQL Learning Path (With Practice Exercises)

I spent 3 weeks learning SQL joins so you don't have to. A beginner-friendly guide to INNER JOIN and LEFT JOIN with real examples, common mistakes, and practice exercises.

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Learn three SQL aggregation patterns that solve real business problems: time-series analysis for revenue trends, customer segmentation for VIP identification, and cross-category matrices for regional performance. These career-focused queries will make you indispensable at work.

3 SQL Aggregation Patterns That Will Make Your Boss Think You're a Data Wizard

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Build Your First Sales Dashboard: SQL Aggregation for Beginners

Learn the critical difference between WHERE and HAVING in SQL. Discover why your aggregate queries fail and the simple fix that will save you hours of debugging.

WHERE vs HAVING: The SQL Mistake That Breaks Your Queries

Learn the 5 most common SQL GROUP BY mistakes beginners make and how to fix them. Understand WHERE vs HAVING, COUNT() variations, NULL handling, and execution order.

5 SQL GROUP BY Mistakes That Make You Look Like a Beginner (And How to Fix Them)

SQL's AVG() function excludes NULL values by design—causing beginners to get technically correct results but wrong business insights. Learn how AVG() handles NULLs, three practical solutions (COALESCE, WHERE, CASE), and a decision framework to choose the right approach for your analytics.

SQL Averages Are Lying to You: The NULL Problem Nobody Talks About

COUNT(*), COUNT(column), and COUNT(DISTINCT) all give different results. Learn which SQL COUNT function to use in every situation with real examples.

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Learn the 5 critical Homebrew mistakes that waste hours of troubleshooting time. Covers PATH issues on Apple Silicon, sudo permission errors, brew doctor warnings, formulae vs casks confusion, and skipping caveats. Includes practical fixes and a quick diagnostic checklist for beginners.

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Why Your Mac Software Installation is Broken (And How to Fix It in 10 Minutes)

Learn how to use Homebrew to install any Mac software with a single command, update everything at once, and never manually download .dmg files again. Perfect for beginners who want to save hours on software management.

How I Stopped Manually Installing Software on Mac (And You Should Too)

Master SQL WHERE clause filtering with this comprehensive guide. Learn essential operators, logical conditions, and common mistakes to avoid.

SQL WHERE Clause Explained: Filter Data Like a Pro in 10 Minutes

Learn the 7 common SQL mistakes beginners make and how to fix them for cleaner, more efficient queries.

7 SQL Mistakes Every Beginner Makes (And How to Fix Them)

Learn how to optimize your note-taking with Markdown, enhancing productivity for students and developers alike.

How to Take Better Notes with Markdown (Student & Developer Edition)

Markdown simplifies writing for developers, ensuring universal compatibility, focus on content, and seamless integration across various platforms and tools.

Why Developers Love Markdown (And 5 Reasons Developers Love Markdown)

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Easydict: The Ultimate macOS Translation Tool for Multilingual Work

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Daily English learning emphasizes consistency over intensity, using sustainable habits and practical tools for steady progress.

Learning English Day by Day

What I wish I knew before running rm -rf — and how you can avoid my mistakes

Linux

cat, less, head, tail, and grep — the only file viewing commands you need

Master find, locate, and search patterns to never lose a file again

How automation tools are transforming movie screenshots into powerful language learning materials — and why teachers report unprecedented student engagement

Typora CSS customization and Markdown editor theme

Writing

Master the most common SQL mistake that causes missing data in your queries

Database

Master database relationships with practical examples using customers and orders

A step-by-step 3-week roadmap with 50 practice exercises to master multi-table SQL queries

Master INNER JOIN and LEFT JOIN with real examples. No fluff, just the SQL knowledge beginners actually need.

Master three aggregation patterns that answer executive questions and fast-track your data career

A portfolio-ready project that teaches SQL aggregation through building 5 real business reports

The one SQL mistake that breaks every beginner's aggregate queries — and how to fix it in seconds

Stop making these common errors and write confident GROUP BY queries every time

Why your salary averages might be wrong (and three ways to fix them)

Understanding COUNT(*), COUNT(column), and COUNT(DISTINCT) with real-world examples

Master Quick Open, Command Palette, and 4 other game-changing shortcuts for a mouse-free workflow

VS Code

Stop struggling with defaults. These 7 essential settings transform VS Code for beginners in 5 minutes.

Set up free image hosting with 10GB storage, unlimited bandwidth, and global CDN in just 15 minutes—no coding required

Markdown

Avoid common Homebrew mistakes that waste hours. Learn the 5 critical errors beginners make and how to fix them in minutes.

macOS

Manual downloads waste hours and create security risks. Here's the 10-minute fix using Homebrew that automates everything.

A beginner's guide to installing and managing macOS software in seconds instead of hours using Homebrew

Complete SQL WHERE clause tutorial for beginners.

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Welcome to Leon's Blog featuring technical tutorials, Notion templates, learning resources, and more. Happy reading!

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Leon shares practical knowledge on programming, productivity, and technical writing, aiming to help others learn and grow.

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