10+ ETL Tester Interview Questions and Answers for Freshers

The interview questions are related to SQL and data manipulation.

• To fetch the last record of a column, you can use the ORDER BY clause with DESC keyword and LIMIT 1.

• Dense rank and rank are both ranking functions in SQL, but dense rank assigns consecutive rank numbers to rows, while rank leaves gaps in the ranking sequence.

• To fetch the end of 5 characters from a string column, you can use the RIGHT function in SQL.

I performed various types of data validation including format validation, completeness validation, and referential integrity validation.

• Format validation: Ensuring that the data is in the correct format as per the defined specifications. For example, validating that a date field is in the format 'YYYY-MM-DD'.

• Completeness validation: Checking if all the required fields are present and populated in the data. For example, ensuring that a customer record has a name, address, and ...read more

Snowflake schema is a normalized form of star schema with additional dimension tables.

• Snowflake schema is a data modeling technique used in data warehousing.

• In snowflake schema, dimensions are normalized into multiple related tables.

• Snowflake schema reduces redundancy and improves data integrity.

• Star schema is a denormalized form of snowflake schema with a single dimension table.

• In star schema, dimensions are not normalized and are directly linked to the fact table.

• Star schem...read more

I prefer not to disclose my current salary as it is confidential.

• It is not appropriate to disclose current salary as it is confidential information.

• I am open to discussing a fair and competitive salary for the position.

• My focus is on finding a challenging role that aligns with my skills and experience.

• I am willing to negotiate based on the job responsibilities and market standards.

Use SQL query with subquery to find second highest salary.

• Use ORDER BY and LIMIT to get the second highest salary.

• Use a subquery to exclude the highest salary from the result set.

• Example: SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees);

Use SQL query with ORDER BY and LIMIT to fetch 5th highest salary.

• Use ORDER BY clause to sort salaries in descending order

• Use LIMIT 1 OFFSET 4 to fetch the 5th highest salary

Yes, I am willing to work at any location.

• I am open to relocation and willing to adapt to new environments.

• I understand that the job may require me to travel or work at different locations.

• I am excited about the opportunity to explore new places and meet new people.

• I am committed to delivering quality work regardless of the location.

Fact tables contain quantitative data that can be measured, while dimension tables contain descriptive attributes related to the facts.

• Fact tables store numerical data such as sales revenue, quantity sold, etc.

• Dimension tables store descriptive attributes like product name, customer name, etc.

• Fact tables are typically larger in size compared to dimension tables.

• Fact tables are connected to dimension tables through foreign keys.

Common validation techniques in ETL testing include data completeness, data accuracy, data transformation, and data quality checks.

• Data completeness validation ensures that all expected data is loaded into the target system.

• Data accuracy validation involves verifying that the data is correctly transformed and loaded without any errors.

• Data transformation validation checks if the data is transformed according to the business rules and requirements.

• Data quality checks involve v...read more