参考URL
http://www.shift-the-oracle.com/sql/merge.html
MERGE INTO USER_MASTER USING USER_MASTER_IMPORT ON ( USER_MASTER.USER_ID = USER_MASTER_IMPORT.USER_ID) -- 既存レコードの更新 WHEN MATCHED THEN UPDATE SET USER_NAME = USER_MASTER_IMPORT.USER_NAME, DEPT_NO = USER_MASTER_IMPORT.DEPT_NO, MODIFIED_ON = SYSDATE -- 新規レコードの作成 WHEN NOT MATCHED THEN INSERT ( USER_ID, USER_NAME, DEPT_NO ) VALUES ( USER_MASTER_IMPORT.USER_ID, USER_MASTER_IMPORT.USER_NAME || '(新人)', USER_MASTER_IMPORT.DEPT_NO )