c# ado.net: nulls dbnull -- there some-more fit syntax?

i've got datetime? i'm perplexing insert domain controlling dbparameter. i'm formulating parameter so:

dbparameter dateprm = updatestmt.createparameter();
dateprm.parametername = "@change_date";

and following i wish put value datetime? dataprm.value while accounting nulls.

i guess primarily i'd clever:

dateprm.value = nullabledate ?? dbnull.value;

but fails error

operator '??' can't receptive operands form 'system.datetime?' 'system.dbnull'

so i speculation wholly works second justification non-nullable chronicle initial argument. following i went for:

dateprm.value = nullabledate.hasvalue ? nullabledate.value : dbnull.value;

but doesn't work either:

type saving countenance can't dynamic since there excellent reworking between 'system.datetime' 'system.dbnull'

but i don't wish modify between those types!

so distant wholly thing i work is:

if (nullabledate.hasvalue)
  dateprm.value = nullabledate.value;
else
  dateprm.value = dbnull.value;

is unequivocally wholly proceed i this? there proceed one-liner controlling ternary user work?

update: i don't unequivocally since ?? chronicle doesn't work. msdn says:

the ?? user advantage left-hand operand null, else advantage right operand.

that's accurately i want!

update2: good kind apparent end:

dateprm.value = nullabledate ?? (object)dbnull.value;