Merge statement is a powerful feature that allow us to perform insert, update and delete operations in a single operation based on a condition.

It is particularly useful for synchronizing data between tables or performing upsert operations.(update if exists, insert if not exists)

Syntax:

MERGE INTO target_table AS target
USING source_table AS source
ON merge_condition
WHEN MATCHED THEN
UPDATE SET column1 = value1, column2 = value2, …
WHEN NOT MATCHED BY TARGET THEN
INSERT (column1, column2, …)
VALUES (value1, value2, …)
WHEN NOT MATCHED BY SOURCE THEN
DELETE;