null값끼리 비교를 하려고 합니다..

아래 비교값 REF.REF_NO와 조건값이 모두 null로 떨어지고 있습니다...

결국  REF.REF_NO(null입니다) = null 인 상태입니다..

그런데 해당 case문에서 리턴되는 null값과 조건값 null의 비교가 제대로 이루어 지지 않습니다...

어떤식으로 비교를 해야 하는지 알려주시면 감사하겠습니다..

좋은하루되세요..^^


//-----------------------------------------------------------------------------------------------------------


 REF.REF_NO =   CASE
                           WHEN (SELECT COUNT( INFO_VAL_TEXT )
                                    FROM PPIT03TB
                                   WHERE INFO_CD = '01552'
                                     AND APPL_END_DATE = '9999-12-31'
                                     AND ETSTATUS = 'A'
                                     AND FK_PLCY_NO = REF.FK_PLCY_NO) = 0  AND REF.REF_NO = ''
                           THEN ''
                           WHEN (SELECT COUNT( INFO_VAL_TEXT )
                                    FROM PPIT03TB
                                   WHERE INFO_CD = '01552'
                                     AND APPL_END_DATE = '9999-12-31'
                                     AND ETSTATUS = 'A'
                                     AND FK_PLCY_NO = REF.FK_PLCY_NO) = 0  AND REF.REF_NO IS NULL
                           THEN NULL
                           ELSE (SELECT INFO_VAL_TEXT
                                    FROM PPIT03TB
                                   WHERE INFO_CD = '01552'
                                     AND APPL_END_DATE = '9999-12-31'
                                     AND ETSTATUS = 'A'
                                     AND FK_PLCY_NO = REF.FK_PLCY_NO)
                      END

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