c# - SqlCeCommand nullable values -

my code:

sqlceconnection sql = new sqlceconnection(@"data source=c:\db.sdf"); sql.open(); cmd = new sqlcecommand("insert xxx(aaa) values(@aaa)", sql); string param = null;  //doesn't work //string param = "blah" //works cmd.parameters.addwithvalue("@aaa", param); cmd.executenonquery(); //(1) sql.close(); 

(1) throws exception when param null. database allows value in collumn aaa null. how can insert null table xxx ?

exception:
parameterized query 'insert xxx(aaa) values(@aaa)' expects parameter value not supplied.

try using dbnull.value instead:

var param = dbnull.value;