Data Engineering Associate with Databricks Practice Exam

What SQL function is used to transform an array into a set of rows?

1. Collect_set

2. Explode

3. Flatten

4. Array_distinct

The correct answer is: Explode

The function that transforms an array into a set of rows is the Explode function. When applied to an array, Explode takes the elements within that array and expands them into separate rows in a result set. Each element of the array becomes a distinct entry in its own row, making it a valuable tool for working with array data types in SQL. This is particularly useful in scenarios where you need to perform further analysis or operations on each individual element of the array. For instance, if you have a dataset with a column containing arrays of values, using the Explode function allows you to normalize your data, facilitating easier aggregations and joins with other tables. In contrast, the other functions mentioned serve different purposes: Collect_set is used to aggregate values into a set, avoiding duplicates; Flatten refers to the process of merging nested data structures but does not necessarily output rows; Array_distinct is used to return distinct values from an array, not to expand it into rows. Understanding the specific function each serves is key to effectively manipulating and analyzing data within a database environment.