10+ HCLTech Data Analyst Interview Questions and Answers

Unwanted safety effect refers to an adverse event or side effect caused by a medication or medical intervention.

• It is an unintended consequence of a medical treatment or intervention

• It can range from mild to severe and can occur immediately or after a period of time

• Examples include allergic reactions, organ damage, and infections

• It is important to monitor and report any unwanted safety effects to ensure patient safety

Data types are the classification of data based on the type of value it holds.

• Data types determine the type of operations that can be performed on the data.

• Examples of data types include integers, strings, booleans, and floats.

• Data types can be categorized as primitive or non-primitive.

• Primitive data types are basic data types like integers and floats, while non-primitive data types are more complex like arrays and objects.

HAVING is used with GROUP BY to filter grouped rows, WHERE is used to filter individual rows.

• HAVING is used with GROUP BY to filter grouped rows based on aggregate functions

• WHERE is used to filter individual rows before any grouping is done

• HAVING is used after GROUP BY in a query, WHERE is used before GROUP BY

• Example: SELECT department, AVG(salary) FROM employees GROUP BY department HAVING AVG(salary) > 50000;

• Example: SELECT * FROM employees WHERE department = 'Sales';

A variable is a value or quantity that can change or vary in a given context or situation.

• Variables are used to store and manipulate data in programming languages.

• They can be assigned different values and used in calculations or comparisons.

• Examples include integers, strings, and booleans.

• Variables can also be used in statistical analysis to represent a characteristic or attribute being measured.

• They are often defined by a name and a data type.

Calculate avg value and standard deviation from given data

• Calculate the average value by summing all data points and dividing by the total number of data points

• Calculate the standard deviation by finding the square root of the average of the squared differences between each data point and the mean

• Example: Data points - 5, 7, 9, 11. Average = (5+7+9+11)/4 = 8. Standard deviation = sqrt(((5-8)^2 + (7-8)^2 + (9-8)^2 + (11-8)^2)/4)

Data warehouse is structured and used for reporting and analysis, while data lake is unstructured and used for exploration and experimentation.

• Data warehouse stores structured data for easy access and analysis.

• Data lake stores unstructured and raw data for exploration and experimentation.

• Data warehouse is typically used for reporting and business intelligence.

• Data lake is used for data science and machine learning projects.

• Data warehouse requires schema-on-write, meaning data...read more

Inner join returns only the matching rows between two tables, while left join returns all rows from the left table and the matching rows from the right table.

• Inner join only includes rows that have a match in both tables

• Left join includes all rows from the left table, even if there is no match in the right table

• Example: Inner join - SELECT * FROM table1 INNER JOIN table2 ON table1.id = table2.id

• Example: Left join - SELECT * FROM table1 LEFT JOIN table2 ON table1.id = table2.i...read more

Incremental refresh is a process of updating only new or changed data in a dataset.

• Identify the key columns that can be used to track changes in the data

• Use date or timestamp columns to filter out new or updated records

• Implement a process to regularly check for new data and update the dataset accordingly

ADSL is a type of internet connection technology, while Blob storage is a type of cloud storage service.

• ADSL (Asymmetric Digital Subscriber Line) is a type of broadband connection that uses existing telephone lines to transmit data.

• Blob storage is a type of cloud storage service provided by platforms like Azure, AWS, and Google Cloud.

• ADSL typically has slower upload speeds compared to download speeds, while Blob storage is designed for storing large amounts of unstructured da...read more

Row level security refers to restricting access to specific rows of data based on user permissions.

• Row level security is implemented by defining filters or conditions on data access at the row level.

• It ensures that users can only see and interact with the data they are authorized to access.

• Connectivity modes refer to the ways in which users can connect to the data source, such as direct query or import mode.