-- DELETE
-- FROM EMP
-- JOIN 
--     EMP_INVALID ON EMP.EMP_CODE = EMP_INVALID.EMP_CODE
-- WHERE
--     VALID_FLG <> 1
WITH INVALID AS (
SELECT EMP_CODE FROM EMP_INVALID
WHERE
    VALID_FLG <> '1'
)
DELETE FROM EMP
WHERE
    EMP_CODE <> (SELECT * FROM INVALID)