Q. Explain the data preprocessing steps in data analysis.

Ans. Data preprocessing transforms the data into a format that is more easily and effectively processed in data mining, machine learning and other data science tasks.
1. Data profiling.
2. Data cleansing.
3. Data reduction.
4. Data transformation.
5. Data enrichment.
6. Data validation.

Q. What Are the Three Stages of Building a Model in Machine Learning?

Ans. The three stages of building a machine learning model are:

Model Building: Choosing a suitable algorithm for the model and train it according to the requirement

Model Testing: Checking the accuracy of the model through the test data

Applying the Model: Making the required changes after testing and use the final model for real-time projects


Q. What are the subsets of SQL?

Ans. The following are the four significant subsets of the SQL:

Data definition language (DDL): It defines the data structure that consists of commands like CREATE, ALTER, DROP, etc.

Data manipulation language (DML): It is used to manipulate existing data in the database. The commands in this category are SELECT, UPDATE, INSERT, etc.

Data control language (DCL): It controls access to the data stored in the database. The commands in this category include GRANT and REVOKE.

Transaction Control Language (TCL): It is used to deal with the transaction operations in the database. The commands in this category are COMMIT, ROLLBACK, SET TRANSACTION, SAVEPOINT, etc.


Q. What is a Parameter in Tableau? Give an Example.

Ans. A parameter is a dynamic value that a customer could select, and you can use it to replace constant values in calculations, filters, and reference lines.
For example, when creating a filter to show the top 10 products based on total profit instead of the fixed value, you can update the filter to show the top 10, 20, or 30 products using a parameter.

SQL Quick Notes to refresh your concepts

Remote Job Opportunities
👇👇
https://t.me/jobs_us_uk

The SQL EXISTS operator tests the existence of any value in a subquery i.e. it executes the outer SQL query only if the subquery is not NULL (empty result-set),making it perfect for validating the presence of related data.

The result of EXISTS is a boolean value either True or False

We can also use the NOT operator to inverse the working of the EXISTS clause. The SQL command executes if the subquery returns an empty result-set.

Many people reached out to me saying telegram may get banned in their countries. So I've decided to create WhatsApp channels based on your interests 👇👇

Free Courses with Certificate: https://whatsapp.com/channel/0029Vamhzk5JENy1Zg9KmO2g

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

MS Excel: https://whatsapp.com/channel/0029VaifY548qIzv0u1AHz3i

Jobs & Internship Opportunities:
https://whatsapp.com/channel/0029VaI5CV93AzNUiZ5Tt226

Web Development: https://whatsapp.com/channel/0029VaiSdWu4NVis9yNEE72z

Python Free Books & Projects: https://whatsapp.com/channel/0029VaiM08SDuMRaGKd9Wv0L

Java Resources: https://whatsapp.com/channel/0029VamdH5mHAdNMHMSBwg1s

Coding Interviews: https://whatsapp.com/channel/0029VammZijATRSlLxywEC3X

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

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

Programming Free Resources: https://whatsapp.com/channel/0029VahiFZQ4o7qN54LTzB17

Data Science Projects: https://whatsapp.com/channel/0029Va4QUHa6rsQjhITHK82y

Learn Data Science & Machine Learning: https://whatsapp.com/channel/0029Va8v3eo1NCrQfGMseL2D

Improve your communication skills: https://whatsapp.com/channel/0029VaiaucV4NVik7Fx6HN2n

Don’t worry Guys your contact number will stay hidden!

ENJOY LEARNING 👍👍

🔅 Most important SQL commands

Frequently asked SQL interview questions for Data Analyst/Data Engineer role-

1 - What is SQL and what are its main features?
2 - Order of writing SQL query?
3- Order of execution of SQL query?
4- What are some of the most common SQL commands?
5- What’s a primary key & foreign key?
6 - All types of joins and questions on their outputs?
7 - Explain all window functions and difference between them?
8 - What is stored procedure?
9 - Difference between stored procedure & Functions in SQL?
10 - What is trigger in SQL?
11 - Difference between where and having?

Data Analysis Checklist
👇👇
https://t.me/learndataanalysis/1135

Do not wait till you've mastered SQL till you apply to your first Data Analyst Job.

You can do both at the same time.

📊Here's a breakdown of SQL interview questions covering various topics:

🔺Basic SQL Concepts:
-Differentiate between SQL and NoSQL databases.
-List common data types in SQL.

🔺Querying:
-Retrieve all records from a table named "Customers."
-Contrast SELECT and SELECT DISTINCT.
-Explain the purpose of the WHERE clause.


🔺Joins:
-Describe types of joins (INNER JOIN, LEFT JOIN, RIGHT JOIN, FULL JOIN).
-Retrieve data from two tables using INNER JOIN.

🔺Aggregate Functions:
-Define aggregate functions and name a few.
-Calculate average, sum, and count of a column in SQL.

🔺Grouping and Filtering:
-Explain the GROUP BY clause and its use.
-Filter SQL query results using the HAVING clause.

🔺Subqueries:
-Define a subquery and provide an example.

🔺Indexes and Optimization:
-Discuss the importance of indexes in a database.
&Optimize a slow-running SQL query.

🔺Normalization and Data Integrity:
-Define database normalization and its significance.
-Enforce data integrity in a SQL database.

🔺Transactions:
-Define a SQL transaction and its purpose.
-Explain ACID properties in database transactions.

🔺Views and Stored Procedures:
-Define a database view and its use.
-Distinguish a stored procedure from a regular SQL query.

🔺Advanced SQL:
-Write a recursive SQL query and explain its use.
-Explain window functions in SQL.

✅👀These questions offer a comprehensive assessment of SQL knowledge, ranging from basics to advanced concepts.

❤️Like if you'd like answers in the next post! 👍

👉Be the first one to know the latest Job openings 👇
https://t.me/jobs_SQL

SQL Interview Ques & ANS 💥👇
https://t.me/learndataanalysis/1156