Explanation

INSERT INTO is the correct SQL keyword for appending new rows to an existing Delta table. Here's why:

• INSERT INTO - This command adds new rows to an existing table without affecting existing data. It's specifically designed for appending data.

Why the other options are incorrect:

• UPDATE - Modifies existing rows in a table, doesn't add new rows
• COPY - Not a standard SQL keyword for table operations; typically used for file operations
• DELETE - Removes rows from a table, doesn't add new data
• UNION - Combines results from multiple SELECT statements, but doesn't directly append to tables

In Databricks with Delta tables, INSERT INTO is the standard way to add new records while maintaining table integrity and supporting ACID transactions.