SQL best practices:

✔ Use EXISTS in place of IN wherever possible
✔ Use table aliases with columns when you are joining multiple tables
✔ Use GROUP BY instead of DISTINCT.
✔ Add useful comments wherever you write complex logic and avoid too many comments.
✔ Use joins instead of subqueries when possible for better performance.
✔ Use WHERE instead of HAVING to define filters on non-aggregate fields
✔ Avoid wildcards at beginning of predicates (something like '%abc' will cause full table scan to get the results)
✔ Considering cardinality within GROUP BY can make it faster (try to consider unique column first in group by list)
✔ Write SQL keywords in capital letters.
✔ Never use select *, always mention list of columns in select clause.
✔ Create CTEs instead of multiple sub queries , it will make your query easy to read.
✔ Join tables using JOIN keywords instead of writing join condition in where clause for better readability.
✔ Never use order by in sub queries , It will unnecessary increase runtime.
✔ If you know there are no duplicates in 2 tables, use UNION ALL instead of UNION for better performance
✔ Always start WHERE clause with 1 = 1.This has the advantage of easily commenting out conditions during debugging a query.
✔ Taking care of NULL values before using equality or comparisons operators. Applying window functions. Filtering the query before joining and having clause.
✔ Make sure the JOIN conditions among two table Join are either keys or Indexed attribute.

Hope it helps :)

Common Requirements for data analyst role 👇

👉 Must be proficient in writing complex SQL Queries.

👉 Understand business requirements in BI context and design data models to transform raw data into meaningful insights.

👉 Connecting data sources, importing data, and transforming data for Business intelligence.

👉 Strong working knowledge in Excel and visualization tools like PowerBI, Tableau or QlikView

👉 Developing visual reports, KPI scorecards, and dashboards using Power BI desktop.

Nowadays, recruiters primary focus on SQL & BI skills for data analyst roles. So try practicing SQL & create some BI projects using Tableau or Power BI.

*Here are some essential WhatsApp Channels with important resources:*

❯ Jobs ➟ https://whatsapp.com/channel/0029Vaxjq5a4dTnKNrdeiZ0J

❯ SQL ➟ https://whatsapp.com/channel/0029VanC5rODzgT6TiTGoa1v

❯ Power BI ➟ https://whatsapp.com/channel/0029Vai1xKf1dAvuk6s1v22c

❯ Data Analysts ➟ https://whatsapp.com/channel/0029VaGgzAk72WTmQFERKh02

❯ Python ➟ https://whatsapp.com/channel/0029VaiM08SDuMRaGKd9Wv0L

I am planning to come up with interview series as well to share some essential questions based on my experience in data analytics field.

Like this post if you want me to start the interview series 👍❤️

Hope it helps :)

🔍 Real-World Data Analyst Tasks & How to Solve Them

As a Data Analyst, your job isn’t just about writing SQL queries or making dashboards—it’s about solving business problems using data. Let’s explore some common real-world tasks and how you can handle them like a pro!

📌 Task 1: Cleaning Messy Data

Before analyzing data, you need to remove duplicates, handle missing values, and standardize formats.

✅ Solution (Using Pandas in Python):

import pandas as pd  
df = pd.read_csv('sales_data.csv')  
df.drop_duplicates(inplace=True)  # Remove duplicate rows  
df.fillna(0, inplace=True)  # Fill missing values with 0  
print(df.head())

💡 Tip: Always check for inconsistent spellings and incorrect date formats!


📌 Task 2: Analyzing Sales Trends

A company wants to know which months have the highest sales.

✅ Solution (Using SQL):

SELECT MONTH(SaleDate) AS Month, SUM(Quantity * Price) AS Total_Revenue  
FROM Sales  
GROUP BY MONTH(SaleDate)  
ORDER BY Total_Revenue DESC;

💡 Tip: Try adding YEAR(SaleDate) to compare yearly trends!


📌 Task 3: Creating a Business Dashboard

Your manager asks you to create a dashboard showing revenue by region, top-selling products, and monthly growth.

✅ Solution (Using Power BI / Tableau):

👉 Add KPI Cards to show total sales & profit

👉 Use a Line Chart for monthly trends

👉 Create a Bar Chart for top-selling products

👉 Use Filters/Slicers for better interactivity

💡 Tip: Keep your dashboards clean, interactive, and easy to interpret!

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Hope it helps :)

Must-Know Power BI Charts & When to Use Them

1. Bar/Column Chart

Use for: Comparing values across categories
Example: Sales by region, revenue by product

2. Line Chart

Use for: Trends over time
Example: Monthly website visits, stock price over years

3. Pie/Donut Chart

Use for: Showing proportions of a whole
Example: Market share by brand, budget distribution

4. Table/Matrix

Use for: Detailed data display with multiple dimensions
Example: Sales by product and month, performance by employee and region

5. Card/KPI

Use for: Displaying single important metrics
Example: Total Revenue, Current Month’s Profit

6. Area Chart

Use for: Showing cumulative trends
Example: Cumulative sales over time

7. Stacked Bar/Column Chart

Use for: Comparing total and subcategories
Example: Sales by region and product category

8. Clustered Bar/Column Chart

Use for: Comparing multiple series side-by-side
Example: Revenue and Profit by product

9. Waterfall Chart

Use for: Visualizing increment/decrement over a value
Example: Profit breakdown – revenue, costs, taxes

10. Scatter Chart

Use for: Relationship between two numerical values
Example: Marketing spend vs revenue, age vs income

11. Funnel Chart

Use for: Showing steps in a process
Example: Sales pipeline, user conversion funnel

12. Treemap

Use for: Hierarchical data in a nested format
Example: Sales by category and sub-category

13. Gauge Chart

Use for: Progress toward a goal
Example: % of sales target achieved

Hope it helps :)

#powerbi

7 Must-Have Tools for Data Analysts in 2025:

✅ SQL – Still the #1 skill for querying and managing structured data
✅ Excel / Google Sheets – Quick analysis, pivot tables, and essential calculations
✅ Python (Pandas, NumPy) – For deep data manipulation and automation
✅ Power BI – Transform data into interactive dashboards
✅ Tableau – Visualize data patterns and trends with ease
✅ Jupyter Notebook – Document, code, and visualize all in one place
✅ Looker Studio – A free and sleek way to create shareable reports with live data.

Perfect blend of code, visuals, and storytelling.

React with ❤️ for free tutorials on each tool

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Hope it helps :)