Insert or update rows according to a match condition; syntax differs by database.
MERGE INTO target USING source ON match_condition WHEN MATCHED THEN UPDATE SET ... WHEN NOT MATCHED THEN INSERT ...;Example (standard-style syntax). Verify supported keywords in your database.
MERGE INTO inventory AS t USING incoming AS s ON (t.sku = s.sku) WHEN MATCHED THEN UPDATE SET quantity = s.quantity WHEN NOT MATCHED THEN INSERT (sku, quantity) VALUES (s.sku, s.quantity);SQLite-oriented variant; dialect behaviour may differ.
INSERT INTO inventory (sku, quantity) VALUES ('A-1', 12) ON CONFLICT (sku) DO UPDATE SET quantity = excluded.quantity;| Option / clause | Description |
|---|---|
Target table / columns | Name the table and columns affected by the statement. |
VALUES / SET / source query | Supply inserted values or assign new values. |
WHERE | Restrict affected rows. Omitting it may change every row. |
RETURNING / OUTPUT | Return changed rows where the dialect supports it. |
Transaction | Use a transaction when several changes must succeed or fail together. |
Review a command and its target before running it. Commands that alter files, services, accounts, disks, permissions or databases may be difficult to reverse. Test in a safe environment and keep backups.