Dell Senior Data Analyst Interview Questions and Answers

Q1. Write a sql query to retrieve the department names along with total number employees in each department
Ans. 
The SQL query retrieves department names and the total number of employees in each department.
• Use the SELECT statement to retrieve the department names and count of employees.

• Join the employee table with the department table using the department ID.

• Group the results by department name.

• Use the COUNT function to calculate the total number of employees in each department.
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Q2. Write a sql query to find total amount of order placed by each customer
Ans. 
This query calculates the total amount of orders placed by each customer.
• Use the GROUP BY clause to group the orders by customer.

• Use the SUM() function to calculate the total amount of each group.

• Join the orders table with the customers table to get the customer names.
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Q1. What is join in sql
Ans. 
Join in SQL is used to combine rows from two or more tables based on a related column between them.
• Join is used to retrieve data from multiple tables based on a related column

• Types of joins include INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL JOIN

• Example: SELECT * FROM table1 INNER JOIN table2 ON table1.column = table2.column
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Q2. What is primary key
Ans. 
Primary key is a unique identifier for each record in a database table.
• Primary key ensures each record in a table is uniquely identified

• It must contain unique values and cannot have NULL values

• Primary key can be a single column or a combination of columns

• Example: 'ID' column in a 'Users' table can be a primary key
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Easy to answer ,asked mostly on sql and other ml topics

Q1. Differencde between sql and nosql
Ans. 
SQL is a relational database management system, while NoSQL is a non-relational database management system.
• SQL databases are table-based and have a predefined schema, while NoSQL databases are document-based, key-value pairs, graph databases, or wide-column stores.

• SQL databases are good for complex queries and transactions, while NoSQL databases are better for hierarchical data storage and real-time web applications.

• Ex...read more
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Q2. What are the regularization in ml
Ans. 
Regularization in machine learning is a technique used to prevent overfitting by adding a penalty term to the model's loss function.
• Regularization helps in reducing the complexity of the model by penalizing large coefficients.

• Common types of regularization include L1 (Lasso) and L2 (Ridge) regularization.

• L1 regularization adds the absolute value of the coefficients to the loss function, promoting sparsity.

• L2 regulariza...read more
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Q1. Exptected salary
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Q2. What do you expect for work
Ans. 
I expect challenging projects, opportunities for growth, collaborative team environment, and work-life balance.
• Challenging projects that allow me to apply my data science skills and learn new techniques

• Opportunities for growth and advancement within the company

• Collaborative team environment where I can share ideas and work together towards common goals

• Work-life balance to ensure I can perform at my best both profession
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Topic was joining and calculating

Basic python questions

Q1. Asked to create a power bi dashboard
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Q1. Had coding test on SQL and Python
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