ON DUPLICATE KEY UPDATE upsert

Oracle MERGE → MySQL ON DUPLICATE KEY UPDATE

MySQL은 MERGE INTO 없음. PK/UNIQUE 기준 upsert:

INSERT INTO table_name (col1, col2, col3)
VALUES ('val1', 'val2', 'val3')
ON DUPLICATE KEY UPDATE
  col2 = 'val4',
  col3 = 'val5';

중복 키 없으면 INSERT, 있으면 UPDATE. PK/UNIQUE 필수.