Data Engineering Associate with Databricks Practice Exam

What is the SQL statement used to combine two tables based on a matching condition?

1. MERGE INTO

2. JOIN

3. UNION

4. INTERSECT

The correct answer is: JOIN

The statement used to combine two tables based on a matching condition is the JOIN statement. A JOIN operation allows you to retrieve records from multiple tables by establishing a relationship between them, often through a common field or key. This capability is crucial for querying data across different datasets that are related, providing a way to create comprehensive datasets based on specific criteria. For instance, when you want to select records from one table that are related to records in another, you can use different types of JOINs, such as INNER JOIN, LEFT JOIN, RIGHT JOIN, and FULL OUTER JOIN, each serving a unique purpose in determining how rows from the tables interact based on the specified condition. The other options serve different functions: MERGE INTO is typically used for merging data from a source table into a target table based on given conditions, whereas UNION combines the result sets of two or more SELECT queries, requiring that they return the same number of columns and compatible data types. INTERSECT retrieves only the rows that are common to both result sets produced by two SELECT queries. However, these are not utilized specifically for combining tables based on matching conditions in the context of retrieving related records.