10+ Data Engineer Intern Interview Questions and Answers

Window functions in SQL are used to perform calculations across a set of rows that are related to the current row.

• Window functions are used to calculate values based on a subset of rows within a table

• They allow you to perform calculations across a set of rows that are related to the current row

• They are often used for running totals, ranking, and moving averages

• Examples of window functions include ROW_NUMBER(), RANK(), and SUM() OVER()

Temporary table in SQL is a table that exists temporarily and is automatically deleted when the session ends.

• Temporary tables are created using CREATE TEMPORARY TABLE statement.

• They are useful for storing intermediate results during complex queries.

• Temporary tables are only visible to the current session and are automatically dropped when the session ends.

Code to remove duplicates from a list of strings

• Create a new empty list to store unique elements

• Iterate through the given list and add elements to the new list only if they are not already present

• Return the new list without duplicates

CTE stands for Common Table Expression, a temporary result set that can be referenced within a SELECT, INSERT, UPDATE, or DELETE statement. Views are virtual tables created by a query.

• CTE is defined using the WITH keyword and can be recursive.

• CTEs are mainly used to simplify complex queries, improve readability, and reduce redundancy.

• Views are saved queries that act as virtual tables, allowing users to query the view as if it were a table.

• Views can be used to hide complexity,...read more

Sort a list in Python

• Use the built-in sorted() function to sort the list in ascending order

• Use the sort() method to sort the list in place

• Use the reverse parameter to sort in descending order

Data engineers are responsible for designing, building, and maintaining the infrastructure that allows for the storage and analysis of data.

• Designing and implementing data pipelines to collect, process, and store data

• Building and maintaining data warehouses and databases

• Optimizing data workflows for efficiency and scalability

• Collaborating with data scientists and analysts to ensure data quality and accessibility

• Implementing data security and privacy measures to protect sensit...read more

Delete removes specific rows, truncate removes all rows, drop removes entire table.

• Delete is used to remove specific rows from a table based on a condition.

• Truncate removes all rows from a table but keeps the table structure.

• Drop removes the entire table along with its structure and data.

• Delete is slower than truncate and drop as it maintains logs for rollback.

• Truncate is faster than delete as it does not maintain logs for rollback.

• Drop is the fastest as it removes the entire...read more

Dataweave is a powerful language used for data integration and transformation.

• Dataweave is used in MuleSoft's Anypoint Platform for data integration and transformation.

• It supports various data formats such as JSON, XML, CSV, and Java objects.

• Dataweave has built-in functions for data manipulation and transformation.

• It can be used to map data from one format to another, filter data, and perform complex transformations.

• Dataweave code can be written in a graphical interface or in...read more

Window functions in SQL are used to perform calculations across a set of table rows related to the current row.

• Window functions are used to calculate values based on a set of rows related to the current row.

• They allow you to perform calculations without grouping the rows into a single output row.

• Common window functions include ROW_NUMBER(), RANK(), DENSE_RANK(), and NTILE().

Create a query to find the total sales amount for each product category.

• Use GROUP BY clause to group the sales data by product category

• Use SUM() function to calculate the total sales amount for each category

Keywords in SQL are essential for querying databases efficiently.

• SELECT

• FROM

• WHERE

• JOIN

• GROUP BY

• ORDER BY

• HAVING

• INSERT INTO

• UPDATE

• DELETE