I just shared this in our @web_dev_bds channel.

If your project are using next.js make sure to upgrade to newest version to avoid security risk

More info: https://thehackernews.com/2025/03/critical-nextjs-vulnerability-allows.html

Here are some additional info about previous SQL database types lesson

🚨 Google just dropped a 68-page whitepaper on Prompt Engineering — perfect for API users!

It’s packed with advanced tips, techniques, and real examples.
Super useful if you're working with LLM APIs or building AI apps!

PDF below 👇

🌸🐣 Happy Easter from the World of Code & Data! 🐰💻

May your day be filled with joy, colorful moments, and beautifully structured queries.
Wishing you and your loved ones a warm, happy, and meaningful Easter!

Your @bigdataspecialist

How discord stores trillions of messages 🧠

An interesting video about one of the biggest challenges in tech world.

This video breaks it down - from the databases they use, to the smart engineering choices that keep everything running smoothly at scale.

No fluff, just a super interesting look at how one of the biggest chat platforms actually works behind the scenes.

Duration ⏰: 1 hour 8 minutes

If you're into system design, scalability, or backend engineering, this one’s a must-watch.

Link

Sorry for not posting for a long time.
I am getting ready for my wedding which will happen in 10 days!🤵👰

Also I will be attending Data Science/AI conference in Malaga (Spain) this week: https://jonthebeach.com/

If you are going to be there please come to say hello 😊

I just got married guys! 😍

This is me and my wife at sunset on our wedding day.

After conference in Spain i come back home and had most amazing wedding 💫

Thanks everyone for your patience. I will start posting regularly soon.

🎯 Master Big Data & Data Engineering — Ultimate Free Resource Pack 🚀

---

🔹 🔥 Pro Tips for Aspiring Data Engineers

1. Learn SQL deeply – it's still the foundation of everything
2. Understand data formats: JSON, Parquet, Avro, ORC
3. Master Apache Spark — it's everywhere
4. Learn to use Airflow for orchestrating workflows
5. Practice writing ETL pipelines — build your own mini data warehouse
6. Get comfortable with cloud platforms (start with AWS/GCP free tiers)
7. Version-control your work using Git + DVC for data versioning
8. Learn Docker & Kubernetes basics — modern data infra depends on it
9. Explore real-time processing: Kafka, Flink, and Spark Streaming
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---

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🕒 10+ weeks
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4. 🌀 Hadoop Tutorial for Beginners – Simplilearn (YouTube)
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👨‍🏫 Industry trainer
💡 Intro to HDFS, MapReduce, and the Hadoop ecosystem


5. 🚀 Google Cloud Data Engineering Quest – Cloud Skills Boost
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📚 Bonus: Free Book

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💡 Open-source guide by a leading Data Engineering YouTuber

One of our subscribers wrote a comment asking for automation testing courses so here you go:

🎯 Ultimate Guide to Automation Testing — For Students & Beginners 🚀
*(All resources 100% FREE & No Signups Required!)*

👨‍💻 Thinking of diving into Automation Testing? Want to boost your QA skills and land a tech job fast? This guide has EVERYTHING you need: tools, tips, free courses, and materials.

---

🔥 What is Automation Testing?
Automation testing uses software tools to run tests on your code automatically — saving time, improving accuracy, and scaling your testing process.

You’ll commonly work with:
✅ Selenium
✅ Playwright
✅ Cypress
✅ JUnit/TestNG
✅ Postman (API Testing)
✅ Jenkins (CI/CD)
✅ Git & GitHub
✅ Python / Java / JS / C#

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🧠 Top FREE Courses (No Login Needed):

🎓 Selenium + Java Full Course:
YouTube (by Mukesh Otwani)
🔗 https://www.youtube.com/watch?v=FRn5J31eAMw

🎓 Playwright JS Testing (2024):
YouTube (by Naveen AutomationLabs)
🔗 https://www.youtube.com/watch?v=jkGAw3m6mAg

🎓 Postman for API Automation Testing:
YouTube (by Automation Step by Step)
🔗 https://www.youtube.com/watch?v=t5n07Ybz7yI

🎓 Cypress Crash Course (JavaScript):
YouTube (by LambdaTest)
🔗 https://www.youtube.com/watch?v=I8N7I0C7D2g

🎓 Jenkins CI/CD for Beginners:
YouTube (TechWorld with Nana)
🔗 https://www.youtube.com/watch?v=FxkSgkFv2TI

---

📚 Free Materials & Docs:

📘 Selenium Documentation:
🔗 https://www.selenium.dev/documentation/

📘 Cypress Docs (Modern Web Testing):
🔗 https://docs.cypress.io/

📘 Playwright Docs (Fast-growing alternative to Selenium):
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📘 Postman Learning Center:
🔗 https://learning.postman.com/

📘 GitHub Learning Lab:
🔗 https://lab.github.com/

---

💡 Top Tips & Tricks for Learners:
🧩 Start with Selenium + Java or Python – they’re industry standards.
🔁 Learn basic loops, conditionals & OOP in your chosen language.
⚙️ Practice writing test scripts for login/logout flows.
🧪 Use dummy sites like:
🔗 https://the-internet.herokuapp.com/
🔗 https://demoqa.com/](https://demoqa.com/
🗂 Use GitHub to track your code from Day 1.
🔧 Start learning CI/CD with Jenkins or GitHub Actions after mastering basics.


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🎁 Bonus: Awesome Practice Projects
✅ Test a Login/Signup form
✅ Automate filling web forms
✅ Write data-driven tests (read data from CSV/Excel)
✅ Automate UI flows with Playwright or Cypress
✅ Automate REST API tests with Postman

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💬 Final Words
Mastering automation testing doesn’t require a degree or \$\$\$. Be consistent, build projects, contribute to GitHub, and keep learning. These free resources are enough to get you job-ready! 💼

💻 *Start today. Build your first automated test. Make future you proud.* 🌱

#AutomationTesting #Selenium #QA

Interesting site with collection of all kind of programming related cheat sheets in one place:

https://overapi.com/

Hey friends! I'm back from my honeymoon 😊

Ready to get back to our regular posts and learning journeys.
Before we dive in, I’ll post a few questions to make sure this channel helps you grow your skills and land that job or internship you’re aiming for! 💼🚀

🔹 SQL Series: Day 5️⃣ – Database & Table Basics

👋 Hey folks! After a few weeks’ break, we’re back with our Monday SQL series specials.
WE are still at basics, today we'll dive into the core building blocks of any database. Think of this as learning the ABCs before writing epic SQL novels.

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🏛 What’s a Database?
A “digital filing cabinet” that holds tables of related info (Users, Products, Orders…).

📋 Tables = Supercharged Spreadsheets
Organized into columns (fields) and rows (records), modeling one real-world entity each.

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+----+---------+-----------------------+  
| id | name    | email                 |  
+----+---------+-----------------------+  
| 1  | Alice   | [email protected]     |  
| 2  | Bob     | [email protected]       |  
| 3  | Carol   | [email protected]     |  
+----+---------+-----------------------+  

* Columns 🔹 Header labels (id, name, email) define the type and name of each data slot—like spreadsheet headers.
* Rows 🔸 Each line is one record (e.g., (2, Bob, [email protected])), representing a single entity.
* Cells ⚡️ Intersection of row+column; e.g., Bob’s email is [email protected].

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🔹 Column types

They tell the database what kind of data each column holds (numbers, text, dates, etc.). Think of them as choosing the right container—glass for water, plastic for cereal.

-—

📚 Column Types at a Glance

* INT – Whole numbers (IDs, counters)
* VARCHAR(n) – Variable-length text up to *n* characters (names, emails)
* DECIMAL(p,s) – Exact decimals with *p* total digits and *s* after the dot (prices, quantities)
* DATE / DATETIME – Calendar dates or timestamps (order dates, signup times)

🔍 Why? Choosing the right type:
• ✅ Saves space (no storing “300 characters” in a “10-char” field)
• ✅ Speeds up comparisons & calculations


That's it for today, next Monday we talk about primary keys 🔑
Please leave reactions to this post if you find this valuable ❤️

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Students 👨‍🎓 11.1 K

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Created by 👨‍🏫 Matti Luukkainen, Kalle Ilves & Jami Kousa (University of Helsinki)

🔗 COURSE LINK: https://fullstackopen.com/en/

🔹 SQL Series: Day 6️⃣ – Mastering the Primary Key

👋 Hey data adventurers! Today we’re shining the spotlight on the Primary Key - the VIP pass that makes every row unique and lightning-fast to find.

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🛠 Origins: Why Primary Keys Were Born

* Prevent Duplicate Records: In early systems, it was all too easy to accidentally insert “two Alices” primary keys ensure each record stays one-of-a-kind.
* Enable Fast Access: As datasets grew, scanning millions of rows was impractical. Keys provided a built-in index for instant lookups.
* Support Relationships: To link data across tables reliably (think Orders → Customers), you need a stable, unique anchor.

---

+----+---------+-----------------------+  
| id | name    | email                 |  
+----+---------+-----------------------+  
| 1  | Alice   | [email protected]     |  
| 2  | Bob     | [email protected]       |  
| 3  | Carol   | [email protected]     |  
+----+---------+-----------------------+  

🔑 What Makes a Primary Key Special?

* Unique – No two rows share the same value.
* Not NULL – Every record must have one.
* Indexed – The database auto-builds an index, so WHERE id = 2 is blazing fast.
* Integrity Enforcer – Prevents duplicates and anchors foreign-key relationships.

---


📋 1. Only One per Table
A table can have just one primary key.

> Even if it’s made of multiple columns (a composite key), you still pick *one* PK to enforce uniqueness.

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🧩 2. Composite Primary Keys
When no single column does the job, team up two (or more) columns:

PRIMARY KEY (order_id, product_id)

This combo ensures each row is unique only when both values match.

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🌱 3. Natural vs. Surrogate Keys
Primary key can be natural or surrogate key:
* Natural Key: Real-world data (e.g., email).
* Surrogate Key: System-generated (e.g., AUTO_INCREMENT or a UUID).

> Tip: Surrogates stay stable; naturals can change (and bite you!).

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🛡 4. Best Practices
• Stable – Pick values that won’t change.
• Minimal – Keep it short; every byte counts.
• Simple – One-column PKs are easiest; use composites only when needed.

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🔐 While the Primary Key is our star today, remember there’s a whole key family waiting in the wings: Super Keys, Candidate Keys, Alternate Keys, Composite Keys, Unique Keys, Foreign Keys, Surrogate Keys… we’ll dive into those soon!