Merge Statement Question

merge into coopeval_owner.students a

   using (select z.rit_uid, z.lastname, z.firstname, z.middlename, z.gender, z.citizenship1, z.citizenship2,
                 z.ethnicity, z.sterm, z.year_level, z.primary_program, z.registered, z.regcoop,
                 z.dce, z.preferred_email, z.gpa, z.cum_gpa, z.completion_term,
                 z.expectedgradterm, z.leavingdate, reasonleaving,
                 z.facadvisorlastname, z.facadvisorfirstname, z.facadvisoruid, z.facadvisoremail, z.advisorlastname,
                 z.advisorfirstname, z.advisoruid, z.advisoremail, z.ntidsupportfacadvisorlastname,
                 z.ntidsupportfacadvisorfirstname, z.ntidsupportfacadvisoruid, z.ntidsupportfacadvisoremail,
                 z.campus, z.numcoops, z.degree_checkout_status, z.numcoops, p.id
            from coopeval_owner.sis_import z,
                 coopeval_owner.programs p
          where z.primary_program = p.code
            and z.rit_uid is not null
            and z.dce is not null) b

                     a.gender = b.gender, a.citizenship1 = b.citizenship1, a.citizenship2 = b.citizenship2,
                     a.ethnicity = b.ethnicity, a.currentterm = b.currentterm, a.currentyear = b.year_level,
                     a.currentdce = b.dce, a.isregistered = b.registered, a.isregisteredcoop = b.regcoop,
                     a.currentemail = b.preferred_email, a.currentgpa = b.gpa, a.currentcumgpa = b.cum_gpa,
                     a.currentcompletionterm = b.completion_term, a.currentexpectedgradterm = b.expectedgradterm,
                     a.currentleavingdate = b.leavingdate, a.reasonleaving = b.currentleavingreason,
                     a.modifieddate = sysdate, a.facadvisorlastname = b.facadvisorlastname,
                     a.facadvisorfirstname = b.facadvisorfirstname, a.facadvisorid = b.facadvisoruid,
                     a.facadvisoremail = b.facadvisoremail, a.advisorlastname = b.advisorlastname, a.advisorfirstname = b.advisorfirstname,
                     a.advisorid = b.advisoruid, a.advisoremail = b.advisoremail, a.currentprogramid = b.id,
                     a.ntidsupportfacadvisorlastname = b.ntidsupportfacadvisorlastname,
                     a.ntidsupportfacadvisorfirstname = b.ntidsupportfacadvisorfirstname,
                     a.ntidsupportfacadvisorid = b.ntidsupportfacadvisoruid, a.ntidsupportfacadvisoremail = b.ntidsupportfacadvisoremail,
                     a.campus = b.campus, a.numcoops = b.numcoops, a.degreecheckoutstatus = b.degree_checkout_status
   when not matched then insert values (b.rituid, b.lastname, b.firstname, b.middlename, b.gender, b.isntid, b.isaalana, b.citizenship1, b.citizenship2,
                     b.ethnicity, b.currentterm, b.currentyear, b.currentprogramid, b.currentsecondaryprogramid, b.currentdce, b.currentemail,
                     b.currentgpa, b.currentcumgpa, b.currentcompletionterm, b.currentexpectedgradterm, 0, 0,
                     b.leavingdate, b.reasonleaving, b.currentadvisorlastname, b.currentadvisorfirstname, b.currentadvisoruid, b.currentadvisoremail,
                     sysdate, sysdate, b.campus, b.facadvisorlastname, b.facadvisorfirstname, b.facadvisormiddlename, b.facadvisoruid,
                     b.facadvisoremail, b.advisorlastname, b.advisorfirstname, b.advisorid, b.advisoremail, b.ntidsupportfacadvisorlastname,
                     b.ntidsupportfacadvisorfirstname, b.ntidsupportfacadvisorid, b.ntidsupportfacadvisoremail, b.numcoops, b.degreecheckoutstatus);