I'm creating a business objects that returns a dataset with a parameterized query, the code works but it runs 10 times slower than what it needs to be, this is the code:

mmDataAccessBase dao = this.GetDataAccessObject();

IDbDataParameter param1 = dao.CreateParameter("@cCamsec", cCamsec);
IDbDataParameter param2 = dao.CreateParameter("@dBegDate", dBegDate);
IDbDataParameter param3 = dao.CreateParameter("@dEndDate", dEndDate);

// Get prices for date range
mmDataSet ds = (mmDataSet)this.GetDataSet(
"SELECT Camsec, Price, Date FROM Price where camsec = @cCamsec and " +
" bestpx = 1 and Date BETWEEN @dBegDate and @dEndDate", param1, param2, param3);

return ds;


As you can see this is pretty simple, the problem starts when this takes way too long, by looking at the SQL profiler, I noticed that cCamsec is been turned into a nvarchar type when sent to SQL, if I take the same query that is been executed and change it to varchar instead, it takes no time at all.

Any help is appretiated.

Thanks
Fabian