10+ Data Quality Analyst Interview Questions and Answers

SQL joins combine rows from two or more tables based on related columns, enabling complex queries and data analysis.

• INNER JOIN: Returns records with matching values in both tables. Example: SELECT * FROM A INNER JOIN B ON A.id = B.id;

• LEFT JOIN (or LEFT OUTER JOIN): Returns all records from the left table and matched records from the right table. Example: SELECT * FROM A LEFT JOIN B ON A.id = B.id;

• RIGHT JOIN (or RIGHT OUTER JOIN): Returns all records from the right table and m...read more

UNION combines results from two queries, removing duplicates; UNION ALL includes all results, retaining duplicates.

• UNION removes duplicate rows from the result set.

• UNION ALL includes all rows, even duplicates.

• Example of UNION: SELECT column1 FROM table1 UNION SELECT column1 FROM table2;

• Example of UNION ALL: SELECT column1 FROM table1 UNION ALL SELECT column1 FROM table2;

• UNION may be slower due to duplicate removal, while UNION ALL is generally faster.

To find the third highest salary, use SQL queries with ORDER BY and LIMIT or subqueries.

• Use 'SELECT DISTINCT salary FROM employees ORDER BY salary DESC LIMIT 1 OFFSET 2;' to get the third highest salary.

• Alternatively, use a subquery: 'SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees WHERE salary < (SELECT MAX(salary) FROM employees));'

• Ensure the salary column is indexed for better performance on large datasets.

Different types of joins in SQL include inner join, outer join, left join, and right join. Handling duplicates can be done using DISTINCT keyword or GROUP BY clause.

• Types of joins in SQL: inner join, outer join, left join, right join

• Handling duplicates in SQL: use DISTINCT keyword or GROUP BY clause

• Handling duplicates in Excel: use Remove Duplicates feature

To find the product wise second highest sales item, sort the sales data for each product and select the second highest value.

• Sort the sales data for each product in descending order

• Select the second value from the sorted list to find the second highest sales item

• Consider ties and handle them accordingly

Yes, I can work EST hours seven days a week, ensuring flexibility and commitment to the role.

• I have experience working in roles that required flexible hours, such as customer support.

• In my previous job, I adjusted my schedule to accommodate team meetings across different time zones.

• I understand the importance of data quality and am willing to prioritize work to meet deadlines, even on weekends.

A stored procedure is a precompiled collection of SQL statements stored in a database for reuse and efficiency.

• Encapsulates complex SQL logic for reuse, e.g., calculating total sales.

• Improves performance by reducing network traffic, e.g., executing multiple queries in one call.

• Enhances security by controlling access to data, e.g., granting execute permissions only.

• Supports parameters for dynamic execution, e.g., passing a customer ID to retrieve specific records.

• Can include e...read more

I aim to enhance data quality processes, develop my analytical skills, and contribute to impactful data-driven decisions in my organization.

• Develop expertise in advanced data quality tools, such as Talend or Informatica, to streamline data cleansing processes.

• Pursue certifications in data analytics and quality management to deepen my knowledge and improve my professional credibility.

• Collaborate with cross-functional teams to implement data governance frameworks that ensure da...read more

I excel in analytical thinking, attention to detail, and effective communication, ensuring high data quality and integrity.

• Strong analytical skills: I can identify patterns and anomalies in data, which helps in pinpointing quality issues.

• Attention to detail: I meticulously review datasets to ensure accuracy, as seen when I reduced errors by 30% in my previous role.

• Effective communication: I can convey complex data quality issues to non-technical stakeholders, facilitating bet...read more

Union combines and removes duplicates, Union All combines all rows including duplicates.

• Union combines the result sets of two or more SELECT statements and removes duplicates

• Union All combines the result sets of two or more SELECT statements including duplicates

• Union is slower than Union All as it involves removing duplicates