Data Science
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Learn how to analyze data effectively and manage databases with ease.

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80% of data problems can be solved with just 16 SQL functions.

I’ve been working with data for years and this truth keeps proving itself:

You don’t need fancy tools.
You need to master the fundamentals.

For data analysts, data scientists, and data engineers:
SQL isn’t optional.
Because data lives in databases.
And databases speak SQL-ish.

Most problems fall into 2 categories:
Aggregate functions (summarise data):

SUM() - Total revenue
COUNT() - Total orders
AVG() - Average purchase value
MIN() - Smallest sale
MAX() - Biggest transaction
STRING_AGG() - Combine text values

Window functions (compare rows):

ROW_NUMBER() - Pagination
RANK() - Leaderboards with ties
DENSE_RANK() - Performance tiers
NTILE() - Split into quartiles
LEAD() - Compare current vs next
LAG() - Compare current vs previous
FIRST_VALUE() - Highest value per group
LAST_VALUE() - Lowest value per group
SUM() OVER() - Running totals
AVG() OVER() - Moving averages

Aggregates collapse rows → one summary result
Window functions keep all rows → add calculations across them
📖🔰 Pandas vs SQL: Most Common Operations Comparison
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📊 Your Data Analyst journey doesn’t start with tools — it starts with a roadmap.

From mastering Excel & SQL ➝ understanding statistics ➝ working with Python & visualization tools ➝ building real-world projects — a clear Data Analyst roadmap can save you months of confusion and wrong learning choices.

If you’re serious about breaking into analytics in 2026, you don’t need random tutorials. You need structured learning, hands-on practice, and industry-relevant skills.
🔅 Python in Excel: Getting Started with Data Analysis

📝 Explore the core concepts and fundamental skills of working with data using Python in Microsoft Excel.

🌐 Author: Joe Marini
🔰 Level: Intermediate
Duration: 1h 40m

📋 Topics: Data Analysis, Microsoft Excel, Python

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Python in Excel: Getting Started with Data Analysis.zip
210.6 MB
📱Data Analysis
📱Python in Excel: Getting Started with Data Analysis
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📖 Types of Keys in SQL
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🔅 Advanced NoSQL for Data Science

📝 Explore the fundamentals of NoSQL. Learn the differences between NoSQL and traditional relational databases, discover how to perform common data science tasks with NoSQL, and more.

🌐 Author: Dan Sullivan
🔰 Level: Advanced
Duration: 1h 54m

📋 Topics: Data Science, NoSQL

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📖Data Science Sandwich
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📖 SQL cheat sheet - Every JOIN explained
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🔰 The 4 Types of SQL Joins

SQL joins combine rows from two or more tables based on a related column. Here are the different types of joins you can use:

1⃣ Inner Join
Returns only the matching rows between both tables. It keeps common data only.

🔢 Left Join
Returns all rows from the left table and matching rows from the right table. If a row in the left table doesn’t have a match in the right table, the right table’s columns will contain NULL values in that row.

🔢 Right Join
Returns all rows from the right table and matching rows from the left table. If no matching record exists in the left table for a record in the right table, the columns from the left table in the result will contain NULL values.

🔢 FULL OUTER JOIN
Returns all rows from both tables, filling in NULL for missing matches.
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🔅 Python Data Structures: Dictionaries

📝 Learn how to use dictionaries to store and retrieve unordered data in Python.

🌐 Author: Deepa Muralidhar
🔰 Level: Beginner
Duration: 57m

📋 Topics: Data Structures, Python

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Python Data Structures: Dictionaries.zip
129.7 MB
📱Data Analysis
📱Python Data Structures: Dictionaries
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📁 The in demand skills of a data analytics
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📖 Top 10 Database Scaling Techniques You Should Know:

1. 𝐈𝐧𝐝𝐞𝐱𝐢𝐧𝐠: Create indexes on frequently queried columns to speed up data retrieval.

2. 𝐕𝐞𝐫𝐭𝐢𝐜𝐚𝐥 𝐒𝐜𝐚𝐥𝐢𝐧𝐠: Upgrade your database server by adding more CPU, RAM, or storage to handle increased load.

3. 𝐂𝐚𝐜𝐡𝐢𝐧𝐠: Store frequently accessed data in-memory (e.g., Redis, Memcached) to reduce database load and improve response time.

4. 𝐒𝐡𝐚𝐫𝐝𝐢𝐧𝐠: Distribute data across multiple servers by splitting the database into smaller, independent shards, allowing for horizontal scaling and improved performance.

5. 𝐑𝐞𝐩𝐥𝐢𝐜𝐚𝐭𝐢𝐨𝐧: Create multiple copies (replicas) of the database across different servers, enabling read queries to be distributed across replicas and improving availability.

6. 𝐐𝐮𝐞𝐫𝐲 𝐎𝐩𝐭𝐢𝐦𝐢𝐳𝐚𝐭𝐢𝐨𝐧: Fine-tune SQL queries, eliminate expensive operations, and leverage indexes effectively to improve execution speed and reduce database load.

7. 𝐂𝐨𝐧𝐧𝐞𝐜𝐭𝐢𝐨𝐧 𝐏𝐨𝐨𝐥𝐢𝐧𝐠: Reduce the overhead of opening/closing database connections by reusing existing ones, improving performance under heavy traffic.

8. 𝐕𝐞𝐫𝐭𝐢𝐜𝐚𝐥 𝐏𝐚𝐫𝐭𝐢𝐭𝐢𝐨𝐧𝐢𝐧𝐠: Split large tables into smaller, more manageable parts (partitions), each containing a subset of the columns/features from the original table.

9. 𝐃𝐞𝐧𝐨𝐫𝐦𝐚𝐥𝐢𝐳𝐚𝐭𝐢𝐨𝐧: Store data in a redundant but structured format to minimize complex joins and speed up read-heavy workloads.

10. 𝐌𝐚𝐭𝐞𝐫𝐢𝐚𝐥𝐢𝐳𝐞𝐝 𝐕𝐢𝐞𝐰𝐬: Pre-compute and store results of complex queries as separate tables to avoid expensive recalculation, reducing database load and improving response times.
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📖 SQL data types
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🔅 Top Five Things to Know in Advanced SQL

📝 Learn advanced SQL concepts and practice them with hands-on exercises.

🌐 Author: Kendall Ruber
🔰 Level: Advanced
Duration: 1h 35m

📋 Topics: SQL

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Top Five Things to Know in Advanced SQL.zip
216.3 MB
📱Data Analysis
📱Top Five Things to Know in Advanced SQL
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