I am very sorry, this is the correction:
Iif(RSKS97.NPCO3>0 , RSKS97.NPCO3,
Iif(RSKS97.NPCO2>0 ,RSKS97.NPCO2,
Iif(RSKS97.NPCO1>0 ,RSKS97.NPCO1,
Iif(RSKS02.NPCOR>0 ,RSKS02.NPCOR,0)))))
No problem for the normalization. As a matter of fact I needed to list in one query certain records which meet...