Casting an SQL smallint to an int in the DAL

pinch · August 1st, 2007, 01:28 PM

I was running into a problem trying to convert an SQL Server smallint column type to an int in my DAL Provider class. Here is a snippet of my code that was failing (the names are different but the pattern is the same as outlined in the book):

Code:

protected virtual SupplementalSheetPlayerDetails GetSupplementalSheetPlayerFromReader(IDataReader reader)  {
  SupplementalSheetPlayerDetails supplementalSheetPlayer = new SupplementalSheetPlayerDetails((int)reader["SupplementalSheetID"],(int)reader["PlayerID"],(int)reader["Seqno"]);
  return supplementalSheetPlayer;
}

In my database, the 'Seqno' column is declared as a smallint, but when I cast it as an integer it causes a runtime error. I solved the error by instead casting it as a short (even though the constructor for the SupplementalSheetPlayerDetails object accepts an integer for the Seqno property) and that seemed to work, but I'm still not sure why I'm getting a casting error in the first place.

Any ideas on why I can cast a smallint as a short but not an int, and also why the smallint is then implicitly cast to an int in the constructor of the entity object?

Thanks.

englere · August 1st, 2007, 10:58 PM

Did you try the Convert class? Maybe:
int i = Convert.ToInt32(val);

Aren't smallint and short both 16 bits wide?

pinch · August 4th, 2007, 11:54 PM

I'll give that a shot, but I thought the whole idea of casting is to convert to a new type; why you can't convert from a 16-bit number to a 32-bit number is beyond me. Thanks for the advice.