select pev.idMaterial 
   
    from st_service v,
         cta_ServiceDefinition vd,
         st_PtyMaterialService pev
    where vd.crServiceDefinition = :c_crServiceDefinition_SectionNo
    and vd.idServiceDefinition = v.idServiceDefinition 
    and v.idService = pev.idPTYMaterialService  
    
    and v.szService = :v_szSectionNo

    and pev.idMaterial <> :p_idMaterial         
    and pev.dtBegin = (
    select max(pev2.dtBegin)
        from st_service v2,
             st_PtyMaterialService pev2 
        where pev2.idMaterial = pev.idMaterial
        and pev2.idPtyMaterialService = v2.idService
        and v2.idServiceDefinition = v.idServiceDefinition
        and pev2.dtBegin <= :p_dtNow
        and (pev2.dtEnd > :p_dtNow or pev2.dtEnd is null)    
        );