If I Were to Start My Data Science Career from Scratch, Here's What I Would Do 👇

1️⃣ Master Advanced SQL

Foundations: Learn database structures, tables, and relationships.

Basic SQL Commands: SELECT, FROM, WHERE, ORDER BY.

Aggregations: Get hands-on with SUM, COUNT, AVG, MIN, MAX, GROUP BY, and HAVING.

JOINs: Understand LEFT, RIGHT, INNER, OUTER, and CARTESIAN joins.

Advanced Concepts: CTEs, window functions, and query optimization.

Metric Development: Build and report metrics effectively.


2️⃣ Study Statistics & A/B Testing

Denoscriptive Statistics: Know your mean, median, mode, and standard deviation.

Distributions: Familiarize yourself with normal, Bernoulli, binomial, exponential, and uniform distributions.

Probability: Understand basic probability and Bayes' theorem.

Intro to ML: Start with linear regression, decision trees, and K-means clustering.

Experimentation Basics: T-tests, Z-tests, Type 1 & Type 2 errors.

A/B Testing: Design experiments—hypothesis formation, sample size calculation, and sample biases.


3️⃣ Learn Python for Data

Data Manipulation: Use pandas for data cleaning and manipulation.

Data Visualization: Explore matplotlib and seaborn for creating visualizations.

Hypothesis Testing: Dive into scipy for statistical testing.

Basic Modeling: Practice building models with scikit-learn.


4️⃣ Develop Product Sense

Product Management Basics: Manage projects and understand the product life cycle.

Data-Driven Strategy: Leverage data to inform decisions and measure success.

Metrics in Business: Define and evaluate metrics that matter to the business.


5️⃣ Hone Soft Skills

Communication: Clearly explain data findings to technical and non-technical audiences.

Collaboration: Work effectively in teams.

Time Management: Prioritize and manage projects efficiently.

Self-Reflection: Regularly assess and improve your skills.


6️⃣ Bonus: Basic Data Engineering

Data Modeling: Understand dimensional modeling and trade-offs in normalization vs. denormalization.

ETL: Set up extraction jobs, manage dependencies, clean and validate data.

Pipeline Testing: Conduct unit testing and ensure data quality throughout the pipeline.

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Essential Python and SQL topics for data analysts 😄👇

Python Topics:

Python Resources - @pythonanalyst

1. Data Structures
   - Lists, Tuples, and Dictionaries
   - NumPy Arrays for numerical data

2. Data Manipulation
   - Pandas DataFrames for structured data
   - Data Cleaning and Preprocessing techniques
   - Data Transformation and Reshaping

3. Data Visualization
   - Matplotlib for basic plotting
   - Seaborn for statistical visualizations
   - Plotly for interactive charts

4. Statistical Analysis
   - Denoscriptive Statistics
   - Hypothesis Testing
   - Regression Analysis

5. Machine Learning
   - Scikit-Learn for machine learning models
   - Model Building, Training, and Evaluation
   - Feature Engineering and Selection

6. Time Series Analysis
   - Handling Time Series Data
   - Time Series Forecasting
   - Anomaly Detection

7. Python Fundamentals
   - Control Flow (if statements, loops)
   - Functions and Modular Code
   - Exception Handling
   - File

SQL Topics:

SQL Resources - @sqlanalyst

1. SQL Basics
   - SQL Syntax
   - SELECT Queries
   - Filters

2. Data Retrieval
   - Aggregation Functions (SUM, AVG, COUNT)
   - GROUP BY

3. Data Filtering
   - WHERE Clause
   - ORDER BY

4. Data Joins
   - JOIN Operations
   - Subqueries

5. Advanced SQL
   - Window Functions
   - Indexing
   - Performance Optimization

6. Database Management
   - Connecting to Databases
   - SQLAlchemy

7. Database Design
   - Data Types
   - Normalization

Remember, it's highly likely that you won't know all these concepts from the start. Data analysis is a journey where the more you learn, the more you grow. Embrace the learning process, and your skills will continually evolve and expand. Keep up the great work!

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Top 10 SQL statements & functions used for data analysis

SELECT: To retrieve data from a database.
FROM: To specify the table or tables from which to retrieve data.
WHERE: To filter data based on specified conditions.
GROUP BY: To group rows with similar values into summary rows.
HAVING: To filter grouped data based on conditions.
ORDER BY: To sort the result set by one or more columns.
COUNT(): To count the number of rows or non-null values in a column.
SUM(): To calculate the sum of values in a numeric column.
AVG(): To calculate the average of values in a numeric column.
JOIN: To combine data from multiple tables based on a related column.

These SQL statements and functions are fundamental for data analysis and querying relational databases effectively.

Hope it helps :)

To effectively learn SQL for a Data Analyst role, follow these steps:

1. Start with a basic course: Begin by taking a basic course on YouTube to familiarize yourself with SQL syntax and terminologies. I recommend the "Learn Complete SQL" playlist from the "techTFQ" YouTube channel.

2. Practice syntax and commands: As you learn new terminologies from the course, practice their syntax on the "w3schools" website. This site provides clear examples of SQL syntax, commands, and functions.

3. Solve practice questions: After completing the initial steps, start solving easy-level SQL practice questions on platforms like "Hackerrank," "Leetcode," "Datalemur," and "Stratascratch." If you get stuck, use the discussion forums on these platforms or ask ChatGPT for help. You can paste the problem into ChatGPT and use a prompt like:
- "Explain the step-by-step solution to the above problem as I am new to SQL, also explain the solution as per the order of execution of SQL."

4. Gradually increase difficulty: Gradually move on to more difficult practice questions. If you encounter new SQL concepts, watch YouTube videos on those topics or ask ChatGPT for explanations.

5. Consistent practice: The most crucial aspect of learning SQL is consistent practice. Regular practice will help you build and solidify your skills.

By following these steps and maintaining regular practice, you'll be well on your way to mastering SQL for a Data Analyst role.

🚀 Essential Python/ Pandas snippets to explore data:
 
1.   .head() - Review top rows
2.   .tail() - Review bottom rows
3.   .info() - Summary of DataFrame
4.   .shape - Shape of DataFrame
5.   .describe() - Denoscriptive stats
6.   .isnull().sum() - Check missing values
7.   .dtypes - Data types of columns
8.   .unique() - Unique values in a column
9.   .nunique() - Count unique values
10.   .value_counts() - Value counts in a column
11.   .corr() - Correlation matrix

Top Excel Formulas Every Data Analyst Should Know

SUM():

Purpose: Adds up a range of numbers.

Example: =SUM(A1:A10)


AVERAGE():

Purpose: Calculates the average of a range of numbers.

Example: =AVERAGE(B1:B10)


COUNT():

Purpose: Counts the number of cells containing numbers.

Example: =COUNT(C1:C10)


IF():

Purpose: Returns one value if a condition is true, and another if false.

Example: =IF(A1 > 10, "Yes", "No")


VLOOKUP():

Purpose: Searches for a value in the first column and returns a value in the same row from another column.

Example: =VLOOKUP(D1, A1:B10, 2, FALSE)


HLOOKUP():

Purpose: Searches for a value in the first row and returns a value in the same column from another row.

Example: =HLOOKUP("Sales", A1:F5, 3, FALSE)


INDEX():

Purpose: Returns the value of a cell based on row and column numbers.

Example: =INDEX(A1:C10, 2, 3)


MATCH():

Purpose: Searches for a value and returns its position in a range.

Example: =MATCH("Product B", A1:A10, 0)


CONCATENATE() or CONCAT():

Purpose: Joins multiple text strings into one.

Example: =CONCATENATE(A1, " ", B1)


TEXT():

Purpose: Formats numbers or dates as text.

Example: =TEXT(A1, "dd/mm/yyyy")

Excel Resources: t.me/excel_data

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📘 SQL Challenges for Data Analytics – With Explanation 🧠

(Beginner ➡️ Advanced)

1️⃣ Select Specific Columns

SELECT name, email FROM users;

This fetches only the name and email columns from the users table.

✔️ Used when you don’t want all columns from a table.


2️⃣ Filter Records with WHERE

SELECT * FROM users WHERE age > 30;

The WHERE clause filters rows where age is greater than 30.

✔️ Used for applying conditions on data.


3️⃣ ORDER BY Clause

SELECT * FROM users ORDER BY registered_at DESC;

Sorts all users based on registered_at in descending order.
✔️ Helpful to get latest data first.


4️⃣ Aggregate Functions (COUNT, AVG)

SELECT COUNT(*) AS total_users, AVG(age) AS avg_age FROM users;

Explanation:
- COUNT(*) counts total rows (users).
- AVG(age) calculates the average age.
✔️ Used for quick stats from tables.


5️⃣ GROUP BY Usage

SELECT city, COUNT(*) AS user_count FROM users GROUP BY city;

Groups data by city and counts users in each group.

✔️ Use when you want grouped summaries.


6️⃣ JOIN Tables

SELECT users.name, orders.amount  
FROM users  
JOIN orders ON users.id = orders.user_id;

Fetches user names along with order amounts by joining users and orders on matching IDs.
✔️ Essential when combining data from multiple tables.


7️⃣ Use of HAVING

SELECT city, COUNT(*) AS total  
FROM users  
GROUP BY city  
HAVING COUNT(*) > 5;

Like WHERE, but used with aggregates. This filters cities with more than 5 users.
✔️ **Use HAVING after GROUP BY.**


8️⃣ Subqueries

SELECT * FROM users  
WHERE salary > (SELECT AVG(salary) FROM users);

Finds users whose salary is above the average. The subquery calculates the average salary first.

✔️ Nested queries for dynamic filtering9️⃣ CASE Statementnt**

SELECT name,  
  CASE  
    WHEN age < 18 THEN 'Teen'  
    WHEN age <= 40 THEN 'Adult'  
    ELSE 'Senior'  
  END AS age_group  
FROM users;

Adds a new column that classifies users into categories based on age.
✔️ Powerful for conditional logic.

🔟 Window Functions (Advanced)

SELECT name, city, score,  
  RANK() OVER (PARTITION BY city ORDER BY score DESC) AS rank  
FROM users;

Ranks users by each city.

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SQL Joins — A Practical Cheatsheet for Professionals

If you’re working with relational data — whether you’re a business analyst, backend dev, or aspiring data scientist — mastering SQL joins isn’t optional. It’s fundamental.

Here’s a concise guide to the most important join types, with real-world use cases:


INNER JOIN

Returns records with matching keys from both tables.
Use case: Show only customers who’ve placed at least one order.


LEFT JOIN (OUTER)

Returns all rows from the left table, and matched rows from the right.
Use case: List all customers, including those with zero orders.


RIGHT JOIN (OUTER)

Returns all rows from the right table. Rarely used, but powerful.
Use case: Show all orders, even if the customer was deleted.


FULL OUTER JOIN

Returns all records from both tables.
Use case: Capture everything — matched and unmatched.


CROSS JOIN

Returns the cartesian product.
Use case: Generate every possible product/supplier combo.


SELF JOIN

Joins a table to itself.
Use case: Show employees and their reporting managers.


Best Practices

Use aliases (A, B) for clean code
Prefer JOIN ON over WHERE for clarity
Always test joins with LIMIT to prevent overloads

If I had to start learning data analyst all over again, I'd follow this:

1- Learn SQL:

---- Joins (Inner, Left, Full outer and Self)
---- Aggregate Functions (COUNT, SUM, AVG, MIN, MAX)
---- Group by and Having clause
---- CTE and Subquery
---- Windows Function (Rank, Dense Rank, Row number, Lead, Lag etc)

2- Learn Excel:

---- Mathematical (COUNT, SUM, AVG, MIN, MAX, etc)
---- Logical Functions (IF, AND, OR, NOT)
---- Lookup and Reference (VLookup, INDEX, MATCH etc)
---- Pivot Table, Filters, Slicers

3- Learn BI Tools:

---- Data Integration and ETL (Extract, Transform, Load)
---- Report Generation
---- Data Exploration and Ad-hoc Analysis
---- Dashboard Creation

4- Learn Python (Pandas) Optional:

---- Data Structures, Data Cleaning and Preparation
---- Data Manipulation
---- Merging and Joining Data (Merging and joining DataFrames -similar to SQL joins)
---- Data Visualization (Basic plotting using Matplotlib and Seaborn)

Hope this helps you 😊

You're STILL a data analyst even if...

- you only use Excel
- you forgot the SQL syntax
- you bombed the big interview
- you don't know how to program
- you did an analysis completely wrong
- you can't remember the right function name
- you have to Google how to do something easy you've done before

You're NOT a data analyst when...
- you give up

SO DON'T GIVE UP! KEEP GOING!

10 Must-Have Habits for Data Analysts 📊🧠

1️⃣ Develop strong Excel & SQL skills
2️⃣ Master data cleaning — it’s 80% of the job
3️⃣ Always validate your data sources
4️⃣ Visualize data clearly (use Power BI/Tableau)
5️⃣ Ask the right business questions
6️⃣ Stay curious — dig deeper into patterns
7️⃣ Document your analysis & assumptions
8️⃣ Communicate insights, not just numbers
9️⃣ Learn basic Python or R for automation
🔟 Keep learning: analytics is always evolving

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