Data Engineering Associate with Databricks Practice Exam

What is the purpose of the ON clause in a MERGE statement?

1. To specify the source table to update

2. To define the condition for matching records

3. To indicate which columns to insert

4. To drop rows that do not match

The correct answer is: To define the condition for matching records

The purpose of the ON clause in a MERGE statement is to define the condition for matching records between the source and target tables. This clause is essential because it allows the database to determine which rows from the source table correspond to which rows in the target table based on specific criteria. The matching condition specified in the ON clause typically involves one or more columns that help identify records that should be updated, inserted, or deleted in the target table during the merge operation. Having a precise and effective matching condition is crucial for achieving the intended behavior of the MERGE statement, as it ensures that the operation affects only the intended rows. This makes the ON clause fundamental to the functionality of a MERGE operation, as it directly influences how data is synchronized between the source and target tables.