A hands-on log of my SQL learning journey, advanced query solutions, and database problem-solving.
Welcome to my official SQL repository! Here I document my step-by-step progress as I solve database challenges, write complex queries, and strengthen my query-writing logic using MySQL.
💡 Workflow Note: I practice queries directly on online platforms and upload my raw
.sqlcode straight through GitHub's web interface — clean, fast, and straight to the point without unnecessary clutter.
This repository uses a two-branch system to keep platform-specific work organized:
| Branch | Description & Focus | Primary Source |
|---|---|---|
🔀 main |
Primary branch containing LeetCode SQL solutions + select merged queries from practice sessions. | LeetCode + Selected Merges |
🔀 sql-practice.com |
Dedicated sandbox branch exclusively for platform practice. | sql-practice.com |
📊 Branch Status: The
sql-practice.combranch is currently a few commits behind themainbranch, but active practice solutions continue to be uploaded there regularly.
- LeetCode SQL: Database problem solving, algorithmic SQL queries, and logic building.
- sql-practice.com: Real-world schema queries, healthcare/hospital datasets, and quick drills.
├── 🪟 Window Functions 📊 ROW_NUMBER(), RANK(), DENSE_RANK(), LEAD(), LAG(), Frame Clauses
├── 🧩 Advanced Logic 🔗 Multi-table JOINs, Correlated Subqueries, CTEs, CASE WHEN
├── 📈 Data Aggregation ⚙️ GROUP BY, HAVING, COUNT(DISTINCT), Conditional SUM/AVG
├── 🔤 String Manipulation ✂️ CONCAT(), SUBSTRING(), REPLACE(), POSITION(), TRIM(), REGEXP
├── 📅 Date & Time Functions ⏱️ DATEDIFF(), DATE_ADD(), DATE_SUB(), EXTRACT(), DATE_FORMAT()
└── ⚡ Basics & CRUD 📁 SELECT, WHERE, ORDER BY, LIMIT, COALESCE(), NULLIF()