#spark

Convert row-level records to column records.

Count occurrences of each character in a string

Count the number of nulls in each column of a table.

Database vs Data Warehouse vs Data Mart vs Data Lake

Define cursors and stored procedures and their use cases.

Given a dataset, perform transformations: Filter rows where sales > 1000, Add a new column calculating a 10% discount on sales, Group data by region and calculate total revenue.

How would you clean the data by filtering out records with null values in user_id?

Managed vs Unmanaged Tables