ddakker님의 블로그

MERGE INTO SEARCH_DATA SD
    USING (SELECT COUNT(DATA) AS C FROM SEARCH_DATA WHERE DATA = 'B') S 
    ON (S.C > 0)
 WHEN MATCHED THEN 
    UPDATE SET SD.CNT = SD.CNT + 1
 WHEN NOT MATCHED THEN 
    INSERT VALUES ('B', 1)