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[Oracle] exists 본문

DB/Oracle

[Oracle] exists

냐옴 2014. 11. 11. 14:25

exists, 서브 쿼리에 결과 행이 있을때만 조건 만족


CASE1

SELECT *

FROM

(

    SELECT 'AA' NM FROM DUAL UNION ALL

    SELECT 'BB' NM FROM DUAL UNION ALL

    SELECT 'CC' NM FROM DUAL

)

WHERE EXISTS

(

    SELECT NULL

    FROM DUAL

    WHERE ROWNUM = 1

)

;


CASE2

SELECT *

FROM

(

    SELECT 'AA' NM FROM DUAL UNION ALL

    SELECT 'BB' NM FROM DUAL UNION ALL

    SELECT 'CC' NM FROM DUAL

)

WHERE EXISTS

(

    SELECT NULL

    FROM DUAL

    WHERE ROWNUM = 0

)

;


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