Oracle Basics

🚀 Pick Your Learning Path

I’ve organized everything here into logical paths—you can jump around, follow the flow, or just learn what you need. It all fits together, but there’s no strict order. Just read, practice, and repeat.

📘 Oracle SQL — Basics to Pro

• Fetching Data: SELECT, FROM, column_name – Learn to fetch all or only the columns you care about.
• Filtering Data: WHERE, BETWEEN, IN, LIKE, IS NULL – Pin down exactly what you need from big tables.
• Sorting Results: ORDER BY, ASC, DESC, ROWNUM – Arrange output by date, name, or top salary.
• Aggregations: COUNT, SUM, AVG, MIN, MAX – Get totals, averages, highs, and lows in your data.
• Grouping Data: GROUP BY, HAVING – Group info like total sales per region.
• Combine Conditions: AND, OR, NOT, =, !=, <, > – Write smart filters with multiple criteria.
• Joins: INNER, LEFT, RIGHT, FULL – Bring in data from multiple tables in meaningful ways.
• Subqueries: Nested SELECTs, EXISTS – Use results from one query in another to filter results.
• Case Logic & Expressions: CASE, DECODE, NVL, COALESCE – Write conditions to format values on the fly.
• Analytical Queries: ROW_NUMBER, RANK, DENSE_RANK, LAG, LEAD – Build powerful reports with ranking and comparisons.
• Set Operations: UNION, UNION ALL, INTERSECT, MINUS – Combine, compare, or filter sets of results.
• Built-In Functions: SYSDATE, TO_CHAR, LENGTH, ROUND, UPPER – Format and convert data types easily.
• Readability & Best Practices: Using aliases, avoiding SELECT *, commenting code — so your queries stay clean and shareable.

📗 Oracle PL/SQL — Project‑Level Skills

• PL/SQL Blocks: DECLARE, BEGIN, EXCEPTION, END — Understand program structure.
• Variables: Using VARCHAR2, NUMBER, BOOLEAN, %TYPE, %ROWTYPE to make code data-aware.
• Control Structures: IF, CASE, LOOP — Handle decision-making and loops easily.
• Cursors: Implicit and explicit cursor with FOR loops — process multi-row data safely.
• Procedures & Functions: Write reusable logic blocks that can be shared across apps.
• Packages: Group related code and definitions to stay organized.
• Exception Handling: Catch errors gracefully—avoid runtime crashes.
• Triggers: Automate tasks when data is inserted, updated, or deleted.
• Real-World Examples: Salary updates, insert logging, audit routines—you’ll write code like this in real life.

⚡ Oracle SQL Performance Tips

• ✅ Always filter on indexed columns.
• ✅ Avoid SELECT * in large tables.
• ✅ Don’t wrap WHERE columns inside functions—breaks indexes.
• ✅ Understand join orders and avoid full table scans.
• ✅ Use EXPLAIN PLAN or Toad/SQL Developer tools to check query cost.
• ✅ Consider using bind variables to avoid hard parse penalties.
• ✅ Break long queries into steps and test performance piece by piece.

🧠 Get Cheat Sheets & Mini Tutorials

Want easy-to-electronic cheat sheets, quick visual guides, and mini code examples? Subscribe and get them straight to your inbox. No spam, ever—just good stuff.

[your-newsletter-form-shortcode]

🙋 Who’s Writing This?

I’m a working Oracle developer and ERP consultant based in Toronto. I’ve built PL/SQL blocks, reports, dashboards, and fixed a ton of production issues. But I remember how confusing it was when I learned it—so I built this site to simplify everything, one concept at a time.

Outside work, I love road trips (like the icy Alcan Highway), exploring tools, and always trying out something new. I put all that learning into simple, no-nonsense tutorials so you don’t fall into the same learning rabbit hole I did.

Learn more about me →

More tutorials, quizzes, and real-case examples are on the way. If you spot a topic marked “coming soon,” it means I’m working on it right now. Stay tuned!