c# - passing NVARCHAR value to stored procedure -

i have stored procedure nvarchar parameter this:

alter procedure [dbo].[hr_companies_getbyidandname]      @companyname nvarchar(100),     @lang int = 1  select * companies (@lang = 1 , namelang1 @companyname )     or     (@lang = 2 , namelang2  @companyname )     ) 

i want supply nvarchar value using syntax:

dbhelper _helper = new dbhelper(); _helper.storedproc = "hr_companies_getbyidandname";                _helper.addparam("@companyname", "n'%" + company.trim() + "%'", sqldbtype.nvarchar); _helper.addparam("@lang", language, sqldbtype.int); return _helper.gettable(); 

but returning null.

when run query without stored procedure select * companies companyname n'%mycompanyname%', returns result.

how add n using dbhelper addparameter?

i'm not sure dbhelper pass nvarchar type values stored procs, following standard way:

var param = new sqlparameter("@companyname ", sqldbtype.nvarchar, size) param.value = company.trim(); 

the 3rd parameter above size of nvarchar parameter declared in sproc using nvarchar(size) syntax. if nvarchar(max) use -1.

also note don't need use "n %" prefix. ado.net layer takes care of it.