...
SET NATURE_CD_2 = 'O'
WHERE TRIM(NATURE_CD_2)
NOT IN ( SELECT NATURE_CD FROM TR98_NATURE );
...
SET NATURE_CD_3 = 'O'
WHERE TRIM(NATURE_CD_3)
NOT IN ( SELECT NATURE_CD FROM TR98_NATURE );
...
UPDATE M70_SDR_TRANSIT SET NATURE_CD_2 = NULL WHERE SUBSTR(NATURE_CD_2,1,1) = ' ' ;
UPDATE M70_SDR_TRANSIT SET NATURE_CD_3 = NULL WHERE SUBSTR(NATURE_CD_3,1,1) = ' ' ;
commit;
--- DOUBLE CHECK FOR INVALID NATURE CODES
...