Top interview SQL questions, including both technical and non-technical questions, along with their answers PART-1

1. What is SQL?
   - Answer: SQL (Structured Query Language) is a standard programming language specifically designed for managing and manipulating relational databases.

2. What are the different types of SQL statements?
   - Answer: SQL statements can be classified into DDL (Data Definition Language), DML (Data Manipulation Language), DCL (Data Control Language), and TCL (Transaction Control Language).

3. What is a primary key?
   - Answer: A primary key is a field (or combination of fields) in a table that uniquely identifies each row/record in that table.

4. What is a foreign key?
   - Answer: A foreign key is a field (or collection of fields) in one table that uniquely identifies a row of another table or the same table. It establishes a link between the data in two tables.

5. What are joins? Explain different types of joins.
   - Answer: A join is an SQL operation for combining records from two or more tables. Types of joins include INNER JOIN, LEFT JOIN (or LEFT OUTER JOIN), RIGHT JOIN (or RIGHT OUTER JOIN), and FULL JOIN (or FULL OUTER JOIN).

6. What is normalization?
   - Answer: Normalization is the process of organizing data to reduce redundancy and improve data integrity. This typically involves dividing a database into two or more tables and defining relationships between them.

7. What is denormalization?
   - Answer: Denormalization is the process of combining normalized tables into fewer tables to improve database read performance, sometimes at the expense of write performance and data integrity.

8. What is stored procedure?
   - Answer: A stored procedure is a prepared SQL code that you can save and reuse. So, if you have an SQL query that you write frequently, you can save it as a stored procedure and then call it to execute it.

9. What is an index?
   - Answer: An index is a database object that improves the speed of data retrieval operations on a table at the cost of additional storage and maintenance overhead.

10. What is a view in SQL?
    - Answer: A view is a virtual table based on the result set of an SQL query. It contains rows and columns, just like a real table, but does not physically store the data.

11. What is a subquery?
    - Answer: A subquery is an SQL query nested inside a larger query. It is used to return data that will be used in the main query as a condition to further restrict the data to be retrieved.

12. What are aggregate functions in SQL?
    - Answer: Aggregate functions perform a calculation on a set of values and return a single value. Examples include COUNT, SUM, AVG (average), MIN (minimum), and MAX (maximum).

13. Difference between DELETE and TRUNCATE?
    - Answer: DELETE removes rows one at a time and logs each delete, while TRUNCATE removes all rows in a table without logging individual row deletions. TRUNCATE is faster but cannot be rolled back.

14. What is a UNION in SQL?
    - Answer: UNION is an operator used to combine the result sets of two or more SELECT statements. It removes duplicate rows between the various SELECT statements.

15. What is a cursor in SQL?
    - Answer: A cursor is a database object used to retrieve, manipulate, and navigate through a result set one row at a time.

16. What is trigger in SQL?
    - Answer: A trigger is a set of SQL statements that automatically execute or "trigger" when certain events occur in a database, such as INSERT, UPDATE, or DELETE.

17. Difference between clustered and non-clustered indexes?
    - Answer: A clustered index determines the physical order of data in a table and can only be one per table. A non-clustered index, on the other hand, creates a logical order and can be many per table.

18. Explain the term ACID.
    - Answer: ACID stands for Atomicity, Consistency, Isolation, and Durability.

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SQL CHEAT SHEET👩‍💻

Here is a quick cheat sheet of some of the most essential SQL commands:

SELECT - Retrieves data from a database

UPDATE - Updates existing data in a database

DELETE - Removes data from a database

INSERT - Adds data to a database

CREATE - Creates an object such as a database or table

ALTER - Modifies an existing object in a database

DROP -Deletes an entire table or database

ORDER BY - Sorts the selected data in an ascending or descending order

WHERE – Condition used to filter a specific set of records from the database

GROUP BY - Groups a set of data by a common parameter

HAVING - Allows the use of aggregate functions within the query

JOIN - Joins two or more tables together to retrieve data

INDEX - Creates an index on a table, to speed up search times.

What seperates a good 𝗗𝗮𝘁𝗮 𝗔𝗻𝗮𝗹𝘆𝘀𝘁 from a great one?

The journey to becoming an exceptional data analyst requires mastering a blend of technical and soft skills.

☑ Technical skills:
- Querying Data with SQL
- Data Visualization (Tableau/PowerBI)
- Data Storytelling and Reporting
- Data Exploration and Analytics
- Data Modeling

☑ Soft Skills:
- Problem Solving
- Communication
- Business Acumen
- Curiosity
- Critical Thinking
- Learning Mindset

But how do you develop these soft skills?

◆ Tackle real-world data projects or case studies. The more complex, the better.

◆ Practice explaining your analysis to non-technical audiences. If they understand, you’ve nailed it!

◆ Learn how industries use data for decision-making. Align your analysis with business outcomes.

◆ Stay curious, ask 'why,' and dig deeper into your data. Don’t settle for surface-level insights.

◆ Keep evolving. Attend webinars, read books, or engage with industry experts regularly.

Essential Excel Functions for Data Analysts 🚀

1️⃣ Basic Functions

SUM() – Adds a range of numbers. =SUM(A1:A10)

AVERAGE() – Calculates the average. =AVERAGE(A1:A10)

MIN() / MAX() – Finds the smallest/largest value. =MIN(A1:A10)


2️⃣ Logical Functions

IF() – Conditional logic. =IF(A1>50, "Pass", "Fail")

IFS() – Multiple conditions. =IFS(A1>90, "A", A1>80, "B", TRUE, "C")

AND() / OR() – Checks multiple conditions. =AND(A1>50, B1<100)


3️⃣ Text Functions

LEFT() / RIGHT() / MID() – Extract text from a string.

=LEFT(A1, 3) (First 3 characters)

=MID(A1, 3, 2) (2 characters from the 3rd position)


LEN() – Counts characters. =LEN(A1)

TRIM() – Removes extra spaces. =TRIM(A1)

UPPER() / LOWER() / PROPER() – Changes text case.


4️⃣ Lookup Functions

VLOOKUP() – Searches for a value in a column.

=VLOOKUP(1001, A2:B10, 2, FALSE)


HLOOKUP() – Searches in a row.

XLOOKUP() – Advanced lookup replacing VLOOKUP.

=XLOOKUP(1001, A2:A10, B2:B10, "Not Found")



5️⃣ Date & Time Functions

TODAY() – Returns the current date.

NOW() – Returns the current date and time.

YEAR(), MONTH(), DAY() – Extracts parts of a date.

DATEDIF() – Calculates the difference between two dates.


6️⃣ Data Cleaning Functions

REMOVE DUPLICATES – Found in the "Data" tab.

CLEAN() – Removes non-printable characters.

SUBSTITUTE() – Replaces text within a string.

=SUBSTITUTE(A1, "old", "new")



7️⃣ Advanced Functions

INDEX() & MATCH() – More flexible alternative to VLOOKUP.

TEXTJOIN() – Joins text with a delimiter.

UNIQUE() – Returns unique values from a range.

FILTER() – Filters data dynamically.

=FILTER(A2:B10, B2:B10>50)



8️⃣ Pivot Tables & Power Query

PIVOT TABLES – Summarizes data dynamically.

GETPIVOTDATA() – Extracts data from a Pivot Table.

POWER QUERY – Automates data cleaning & transformation.


You can find Free Excel Resources here: https://t.iss.one/excel_data

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#dataanalytics

🔍 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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Learn SQL from basic to advanced level in 30 days

Week 1: SQL Basics

Day 1: Introduction to SQL and Relational Databases

Overview of SQL Syntax

Setting up a Database (MySQL, PostgreSQL, or SQL Server)


Day 2: Data Types (Numeric, String, Date, etc.)

Writing Basic SQL Queries:

SELECT, FROM

Day 3: WHERE Clause for Filtering Data

Using Logical Operators:

AND, OR, NOT

Day 4: Sorting Data: ORDER BY

Limiting Results: LIMIT and OFFSET

Understanding DISTINCT

Day 5: Aggregate Functions:

COUNT, SUM, AVG, MIN, MAX


Day 6: Grouping Data: GROUP BY and HAVING

Combining Filters with Aggregations


Day 7: Review Week 1 Topics with Hands-On Practice

Solve SQL Exercises on platforms like HackerRank, LeetCode, or W3Schools


Week 2: Intermediate SQL

Day 8: SQL JOINS:

INNER JOIN, LEFT JOIN

Day 9: SQL JOINS Continued: RIGHT JOIN, FULL OUTER JOIN, SELF JOIN

Day 10: Working with NULL Values

Using Conditional Logic with CASE Statements

Day 11: Subqueries: Simple Subqueries (Single-row and Multi-row)

Correlated Subqueries

Day 12: String Functions:

CONCAT, SUBSTRING, LENGTH, REPLACE

Day 13: Date and Time Functions: NOW, CURDATE, DATEDIFF, DATEADD

Day 14: Combining Results: UNION, UNION ALL, INTERSECT, EXCEPT

Review Week 2 Topics and Practice

Week 3: Advanced SQL

Day 15: Common Table Expressions (CTEs)

WITH Clauses and Recursive Queries

Day 16: Window Functions:

ROW_NUMBER, RANK, DENSE_RANK, NTILE

Day 17: More Window Functions:

LEAD, LAG, FIRST_VALUE, LAST_VALUE


Day 18: Creating and Managing Views

Temporary Tables and Table Variables

Day 19: Transactions and ACID Properties

Working with Indexes for Query Optimization

Day 20: Error Handling in SQL

Writing Dynamic SQL Queries


Day 21: Review Week 3 Topics with Complex Query Practice

Solve Intermediate to Advanced SQL Challenges



Week 4: Database Management and Advanced Applications

Day 22: Database Design and Normalization:

1NF, 2NF, 3NF


Day 23: Constraints in SQL:
PRIMARY KEY, FOREIGN KEY, UNIQUE, CHECK, DEFAULT


Day 24: Creating and Managing Indexes

Understanding Query Execution Plans

Day 25: Backup and Restore Strategies in SQL

Role-Based Permissions

Day 26: Pivoting and Unpivoting Data

Working with JSON and XML in SQL

Day 27: Writing Stored Procedures and Functions

Automating Processes with Triggers

Day 28: Integrating SQL with Other Tools (e.g., Python, Power BI, Tableau)

SQL in Big Data: Introduction to NoSQL

Day 29: Query Performance Tuning:

Tips and Tricks to Optimize SQL Queries


Day 30: Final Review of All Topics

Attempt SQL Projects or Case Studies (e.g., analyzing sales data, building a reporting dashboard)

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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

Top 10 Excel functions for data analysis

SUMIF/SUMIFS: Sum values based on specified conditions, allowing you to aggregate data selectively.
AVERAGE: Calculate the average of a range of numbers, useful for finding central tendencies.
COUNT/COUNTIF/COUNTIFS: Count the number of cells that meet specific criteria, helping with data profiling.
MAX/MIN: Find the maximum or minimum value in a dataset, useful for identifying extremes.
IF/IFERROR: Perform conditional calculations and handle errors in data gracefully.
VLOOKUP/HLOOKUP: Search for a value in a table and return related information, aiding data retrieval.
PivotTables: Dynamically summarize and analyze data, making it easier to draw insights.
INDEX/MATCH: Retrieve data based on criteria, providing more flexible lookup capabilities than VLOOKUP.
TEXT and DATE Functions: Manipulate text strings and work with date values effectively.
Statistical Functions (e.g., AVERAGEIFS, STDEV, CORREL): Perform advanced statistical analysis on your data.

These functions form the foundation for many data analysis tasks in Excel and are essential for anyone working data regularly.

Hope it helps :)

Data Analyst Learning Plan in 2025

|-- Week 1: Introduction to Data Analysis
| |-- Data Analysis Fundamentals
| | |-- What is Data Analysis?
| | |-- Types of Data Analysis
| | |-- Data Analysis Workflow
| |-- Tools and Environment Setup
| | |-- Overview of Tools (Excel, SQL)
| | |-- Installing Necessary Software
| | |-- Setting Up Your Workspace
| |-- First Data Analysis Project
| | |-- Data Collection
| | |-- Data Cleaning
| | |-- Basic Data Exploration
|
|-- Week 2: Data Collection and Cleaning
| |-- Data Collection Methods
| | |-- Primary vs. Secondary Data
| | |-- Web Scraping
| | |-- APIs
| |-- Data Cleaning Techniques
| | |-- Handling Missing Values
| | |-- Data Transformation
| | |-- Data Normalization
| |-- Data Quality
| | |-- Ensuring Data Accuracy
| | |-- Data Integrity
| | |-- Data Validation
|
|-- Week 3: Data Exploration and Visualization
| |-- Exploratory Data Analysis (EDA)
| | |-- Descriptive Statistics
| | |-- Data Distribution
| | |-- Correlation Analysis
| |-- Data Visualization Basics
| | |-- Choosing the Right Chart Type
| | |-- Creating Basic Charts
| | |-- Customizing Visuals
| |-- Advanced Data Visualization
| | |-- Interactive Dashboards
| | |-- Storytelling with Data
| | |-- Data Presentation Techniques
|
|-- Week 4: Statistical Analysis
| |-- Introduction to Statistics
| | |-- Descriptive vs. Inferential Statistics
| | |-- Probability Theory
| |-- Hypothesis Testing
| | |-- Null and Alternative Hypotheses
| | |-- t-tests, Chi-square tests
| | |-- p-values and Significance Levels
| |-- Regression Analysis
| | |-- Simple Linear Regression
| | |-- Multiple Linear Regression
| | |-- Logistic Regression
|
|-- Week 5: SQL for Data Analysis
| |-- SQL Basics
| | |-- SQL Syntax
| | |-- Select, Insert, Update, Delete
| |-- Advanced SQL
| | |-- Joins and Subqueries
| | |-- Window Functions
| | |-- Stored Procedures
| |-- SQL for Data Analysis
| | |-- Data Aggregation
| | |-- Data Transformation
| | |-- SQL for Reporting
|
|-- Week 6-8: Python for Data Analysis
| |-- Python Basics
| | |-- Python Syntax
| | |-- Data Types and Structures
| | |-- Functions and Loops
| |-- Data Analysis with Python
| | |-- NumPy for Numerical Data
| | |-- Pandas for Data Manipulation
| | |-- Matplotlib and Seaborn for Visualization
| |-- Advanced Data Analysis in Python
| | |-- Time Series Analysis
| | |-- Machine Learning Basics
| | |-- Data Pipelines
|
|-- Week 9-11: Real-world Applications and Projects
| |-- Capstone Project
| | |-- Project Planning
| | |-- Data Collection and Preparation
| | |-- Building and Optimizing Models
| | |-- Creating and Publishing Reports
| |-- Case Studies
| | |-- Business Use Cases
| | |-- Industry-specific Solutions
| |-- Integration with Other Tools
| | |-- Data Analysis with Excel
| | |-- Data Analysis with R
| | |-- Data Analysis with Tableau/Power BI
|
|-- Week 12: Post-Project Learning
| |-- Data Analysis for Business Intelligence
| | |-- KPI Dashboards
| | |-- Financial Reporting
| | |-- Sales and Marketing Analytics
| |-- Advanced Data Analysis Topics
| | |-- Big Data Technologies
| | |-- Cloud Data Warehousing
| |-- Continuing Education
| | |-- Advanced Data Analysis Techniques
| | |-- Community and Forums
| | |-- Keeping Up with Updates
|
|-- Resources and Community
| |-- Online Courses (edX, Udemy)
| |-- Data Analysis Blogs
| |-- Data Analysis Communities

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Essential Power BI Interview Questions for Data Analysts:

🔹 Basic Power BI Concepts:

Define Power BI and its core components.

Differentiate between Power BI Desktop, Service, and Mobile.


🔹 Data Connectivity and Transformation:

Explain Power Query and its purpose in Power BI.

Describe common data sources that Power BI can connect to.


🔹 Data Modeling:

What is data modeling in Power BI, and why is it important?

Explain relationships in Power BI. How do one-to-many and many-to-many relationships work?


🔹 DAX (Data Analysis Expressions):

Define DAX and its importance in Power BI.

Write a DAX formula to calculate year-over-year growth.

Differentiate between calculated columns and measures.


🔹 Visualization:

Describe the types of visualizations available in Power BI.

How would you use slicers and filters to enhance user interaction?


🔹 Reports and Dashboards:

What is the difference between a Power BI report and a dashboard?

Explain the process of creating a dashboard in Power BI.


🔹 Publishing and Sharing:

How can you publish a Power BI report to the Power BI Service?

What are the options for sharing a report with others?


🔹 Row-Level Security (RLS):

Define Row-Level Security in Power BI and explain how to implement it.


🔹 Power BI Performance Optimization:

What techniques would you use to optimize a slow Power BI report?

Explain the role of aggregations and data reduction strategies.


🔹 Power BI Gateways:

Describe an on-premises data gateway and its purpose in Power BI.

How would you manage data refreshes with a gateway?


🔹 Advanced Power BI:

Explain incremental data refresh and how to set it up.

Discuss Power BI’s AI and Machine Learning capabilities.


🔹 Deployment Pipelines and Version Control:

How would you use deployment pipelines for development, testing, and production?

Explain version control best practices in Power BI.

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You can find detailed answers here

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Here are some commonly asked SQL interview questions along with brief answers:

1. What is SQL?
- SQL stands for Structured Query Language, used for managing and manipulating relational databases.

2. What are the types of SQL commands?
- SQL commands can be broadly categorized into four types: Data Definition Language (DDL), Data Manipulation Language (DML), Data Control Language (DCL), and Transaction Control Language (TCL).

3. What is the difference between CHAR and VARCHAR data types?
- CHAR is a fixed-length character data type, while VARCHAR is a variable-length character data type. CHAR will always occupy the same amount of storage space, while VARCHAR will only use the necessary space to store the actual data.

4. What is a primary key?
- A primary key is a column or a set of columns that uniquely identifies each row in a table. It ensures data integrity by enforcing uniqueness and can be used to establish relationships between tables.

5. What is a foreign key?
- A foreign key is a column or a set of columns in one table that refers to the primary key in another table. It establishes a relationship between two tables and ensures referential integrity.

6. What is a JOIN in SQL?
- JOIN is used to combine rows from two or more tables based on a related column between them. There are different types of JOINs, including INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN.

7. What is the difference between INNER JOIN and OUTER JOIN?
- INNER JOIN returns only the rows that have matching values in both tables, while OUTER JOIN (LEFT, RIGHT, FULL) returns all rows from one or both tables, with NULL values in columns where there is no match.

8. What is the difference between GROUP BY and ORDER BY?
- GROUP BY is used to group rows that have the same values into summary rows, typically used with aggregate functions like SUM, COUNT, AVG, etc., while ORDER BY is used to sort the result set based on one or more columns.

9. What is a subquery?
- A subquery is a query nested within another query, used to return data that will be used in the main query. Subqueries can be used in SELECT, INSERT, UPDATE, and DELETE statements.

10. What is normalization in SQL?
- Normalization is the process of organizing data in a database to reduce redundancy and dependency. It involves dividing large tables into smaller tables and defining relationships between them to improve data integrity and efficiency.

Around 90% questions will be asked from sql in data analytics interview, so please make sure to practice SQL skills using websites like stratascratch. ☺️💪

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.

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Data Analyst Interview Questions 👇

1.How to create filters in Power BI?

Filters are an integral part of Power BI reports. They are used to slice and dice the data as per the dimensions we want. Filters are created in a couple of ways.

Using Slicers: A slicer is a visual under Visualization Pane. This can be added to the design view to filter our reports. When a slicer is added to the design view, it requires a field to be added to it. For example- Slicer can be added for Country fields. Then the data can be filtered based on countries.
Using Filter Pane: The Power BI team has added a filter pane to the reports, which is a single space where we can add different fields as filters. And these fields can be added depending on whether you want to filter only one visual(Visual level filter), or all the visuals in the report page(Page level filters), or applicable to all the pages of the report(report level filters)


2.How to sort data in Power BI?

Sorting is available in multiple formats. In the data view, a common sorting option of alphabetical order is there. Apart from that, we have the option of Sort by column, where one can sort a column based on another column. The sorting option is available in visuals as well. Sort by ascending and descending option by the fields and measure present in the visual is also available.


3.How to convert pdf to excel?

Open the PDF document you want to convert in XLSX format in Acrobat DC.
Go to the right pane and click on the “Export PDF” option.
Choose spreadsheet as the Export format.
Select “Microsoft Excel Workbook.”
Now click “Export.”
Download the converted file or share it.


4. How to enable macros in excel?

Click the file tab and then click “Options.”
A dialog box will appear. In the “Excel Options” dialog box, click on the “Trust Center” and then “Trust Center Settings.”
Go to the “Macro Settings” and select “enable all macros.”
Click OK to apply the macro settings.

1. List the different types of relationships in SQL.

One-to-One - This can be defined as the relationship between two tables where each record in one table is associated with the maximum of one record in the other table.
One-to-Many & Many-to-One - This is the most commonly used relationship where a record in a table is associated with multiple records in the other table.
Many-to-Many - This is used in cases when multiple instances on both sides are needed for defining a relationship.
Self-Referencing Relationships - This is used when a table needs to define a relationship with itself.

2. What are the different views available in Power BI Desktop?

There are three different views in Power BI, each of which serves another purpose:
Report View - In this view, users can add visualizations and additional report pages and publish the same on the portal.
Data View - In this view, data shaping can be performed using Query Editor tools.
Model View - In this view, users can manage relationships between complex datasets.


3. What are macros in Excel?

Excel allows you to automate the tasks you do regularly by recording them into macros. So, a macro is an action or a set of them that you can perform n number of times. For example, if you have to record the sales of each item at the end of the day, you can create a macro that will automatically calculate the sales, profits, loss, etc and use the same for the future instead of manually calculating it every day.

Q1: How do you ensure data consistency and integrity in a data warehousing environment?

Ans: I implement data validation checks, use constraints like primary and foreign keys, and ensure that ETL processes have error-handling mechanisms. Regular audits and data reconciliation processes are also set up to ensure data accuracy and consistency.

Q2: Describe a situation where you had to design a star schema for a data warehousing project.

Ans: For a retail sales data warehousing project, I designed a star schema with a central fact table containing sales transactions. Surrounding this were dimension tables like Products, Stores, Time, and Customers. This structure allowed for efficient querying and reporting of sales metrics across various dimensions.

Q3: How would you use data analytics to assess credit risk for loan applicants?

Ans: I'd analyze the applicant's financial history, including credit score, income, employment stability, and existing debts. Using predictive modeling, I'd assess the probability of default based on historical data of similar applicants. This would help in making informed lending decisions.

Q4: Describe a situation where you had to ensure data security for sensitive financial data.

Ans: While working on a project involving customer transaction data, I ensured that all data was encrypted both at rest and in transit. I also implemented role-based access controls, ensuring that only authorized personnel could access specific data sets. Regular audits and penetration tests were conducted to identify and rectify potential vulnerabilities.

Practise these 5 intermediate SQL interview questions today!

1. Write a SQL query for cumulative sum of salary of each employee from Jan to July. (Column name – Emp_id, Month, Salary).

2. Write a SQL query to display year on year growth for each product. (Column name – transaction_id, Product_id, transaction_date, spend). Output will have year, product_id & yoy_growth.

3. Write a SQL query to find the numbers which consecutively occurs 3 times. (Column name – id, numbers)

4. Write a SQL query to find the days when temperature was higher than its previous dates. (Column name – Days, Temp)

5. Write a SQL query to find the nth highest salary from the table emp. (Column name – id, salary)

SQL CHEAT SHEET👩‍💻

SQL is a language used to communicate with databases it stands for Structured Query Language and is used by database administrators and developers alike to write queries that are used to interact with the database. Here is a quick cheat sheet of some of the most essential SQL commands:

SELECT - Retrieves data from a database

UPDATE - Updates existing data in a database

DELETE - Removes data from a database

INSERT - Adds data to a database

CREATE - Creates an object such as a database or table

ALTER - Modifies an existing object in a database

DROP -Deletes an entire table or database

ORDER BY - Sorts the selected data in an ascending or descending order

WHERE – Condition used to filter a specific set of records from the database

GROUP BY - Groups a set of data by a common parameter

HAVING - Allows the use of aggregate functions within the query

JOIN - Joins two or more tables together to retrieve data

INDEX - Creates an index on a table, to speed up search times.

𝗛𝗼𝘄 𝘁𝗼 𝗕𝗲𝗰𝗼𝗺𝗲 𝗮 𝗝𝗼𝗯-𝗥𝗲𝗮𝗱𝘆 𝗗𝗮𝘁𝗮 𝗦𝗰𝗶𝗲𝗻𝘁𝗶𝘀𝘁 𝗳𝗿𝗼𝗺 𝗦𝗰𝗿𝗮𝘁𝗰𝗵 (𝗘𝘃𝗲𝗻 𝗶𝗳 𝗬𝗼𝘂’𝗿𝗲 𝗮 𝗕𝗲𝗴𝗶𝗻𝗻𝗲𝗿!) 📊

Wanna break into data science but feel overwhelmed by too many courses, buzzwords, and conflicting advice? You’re not alone.

Here’s the truth: You don’t need a PhD or 10 certifications. You just need the right skills in the right order.

Let me show you a proven 5-step roadmap that actually works for landing data science roles (even entry-level) 👇

🔹 Step 1: Learn the Core Tools (This is Your Foundation)

Focus on 3 key tools first—don’t overcomplicate:

✅ Python – NumPy, Pandas, Matplotlib, Seaborn
✅ SQL – Joins, Aggregations, Window Functions
✅ Excel – VLOOKUP, Pivot Tables, Data Cleaning

🔹 Step 2: Master Data Cleaning & EDA (Your Real-World Skill)

Real data is messy. Learn how to:

✅ Handle missing data, outliers, and duplicates
✅ Visualize trends using Matplotlib/Seaborn
✅ Use groupby(), merge(), and pivot_table()

🔹 Step 3: Learn ML Basics (No Fancy Math Needed)

Stick to core algorithms first:

✅ Linear & Logistic Regression
✅ Decision Trees & Random Forest
✅ KMeans Clustering + Model Evaluation Metrics

🔹 Step 4: Build Projects That Prove Your Skills

One strong project > 5 courses. Create:

✅ Sales Forecasting using Time Series
✅ Movie Recommendation System
✅ HR Analytics Dashboard using Python + Excel
📍 Upload them on GitHub. Add visuals, write a good README, and share on LinkedIn.

🔹 Step 5: Prep for the Job Hunt (Your Personal Brand Matters)

✅ Create a strong LinkedIn profile with keywords like “Aspiring Data Scientist | Python | SQL | ML”
✅ Add GitHub link + Highlight your Projects
✅ Follow Data Science mentors, engage with content, and network for referrals

🎯 No shortcuts. Just consistent baby steps.

Every pro data scientist once started as a beginner. Stay curious, stay consistent.

Free Data Science Resources: https://whatsapp.com/channel/0029VauCKUI6WaKrgTHrRD0i

ENJOY LEARNING 👍👍

Complete roadmap to learn Python for data analysis

Step 1: Fundamentals of Python

1. Basics of Python Programming
- Introduction to Python
- Data types (integers, floats, strings, booleans)
- Variables and constants
- Basic operators (arithmetic, comparison, logical)

2. Control Structures
- Conditional statements (if, elif, else)
- Loops (for, while)
- List comprehensions

3. Functions and Modules
- Defining functions
- Function arguments and return values
- Importing modules
- Built-in functions vs. user-defined functions

4. Data Structures
- Lists, tuples, sets, dictionaries
- Manipulating data structures (add, remove, update elements)

Step 2: Advanced Python
1. File Handling
- Reading from and writing to files
- Working with different file formats (txt, csv, json)

2. Error Handling
- Try, except blocks
- Handling exceptions and errors gracefully

3. Object-Oriented Programming (OOP)
- Classes and objects
- Inheritance and polymorphism
- Encapsulation

Step 3: Libraries for Data Analysis
1. NumPy
- Understanding arrays and array operations
- Indexing, slicing, and iterating
- Mathematical functions and statistical operations

2. Pandas
- Series and DataFrames
- Reading and writing data (csv, excel, sql, json)
- Data cleaning and preparation
- Merging, joining, and concatenating data
- Grouping and aggregating data

3. Matplotlib and Seaborn
- Data visualization with Matplotlib
- Plotting different types of graphs (line, bar, scatter, histogram)
- Customizing plots
- Advanced visualizations with Seaborn

Step 4: Data Manipulation and Analysis
1. Data Wrangling
- Handling missing values
- Data transformation
- Feature engineering

2. Exploratory Data Analysis (EDA)
- Descriptive statistics
- Data visualization techniques
- Identifying patterns and outliers

3. Statistical Analysis
- Hypothesis testing
- Correlation and regression analysis
- Probability distributions

Step 5: Advanced Topics
1. Time Series Analysis
- Working with datetime objects
- Time series decomposition
- Forecasting models

2. Machine Learning Basics
- Introduction to machine learning
- Supervised vs. unsupervised learning
- Using Scikit-Learn for machine learning
- Building and evaluating models

3. Big Data and Cloud Computing
- Introduction to big data frameworks (e.g., Hadoop, Spark)
- Using cloud services for data analysis (e.g., AWS, Google Cloud)

Step 6: Practical Projects
1. Hands-on Projects
- Analyzing datasets from Kaggle
- Building interactive dashboards with Plotly or Dash
- Developing end-to-end data analysis projects

2. Collaborative Projects
- Participating in data science competitions
- Contributing to open-source projects

👨‍💻 FREE Resources to Learn & Practice Python 

1. https://www.freecodecamp.org/learn/data-analysis-with-python/#data-analysis-with-python-course
2. https://www.hackerrank.com/domains/python
3. https://www.hackerearth.com/practice/python/getting-started/numbers/practice-problems/
4. https://t.iss.one/PythonInterviews
5. https://www.w3schools.com/python/python_exercises.asp
6. https://t.iss.one/pythonfreebootcamp/134
7. https://t.iss.one/pythonanalyst
8. https://pythonbasics.org/exercises/
9. https://t.iss.one/pythondevelopersindia/300
10. https://www.geeksforgeeks.org/python-programming-language/learn-python-tutorial
11. https://t.iss.one/pythonspecialist/33

Join @free4unow_backup for more free resources

ENJOY LEARNING 👍👍