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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🔹 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.

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+----+---------+-----------------------+  
| 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.

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📋 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!

Bash brackets cheat sheet

For all those bash people out there, this might be useful

Man gotta love bash, right? 😁