SQL querying problem

[C# Programming]

Hi!

I'm trying to check my database if an entry on a field is already exists in the DB.

My Sql command is this:

string Sqlcommand = "SELECT Name FROM Students WHERE Id LIKE '" + TextBox1 + "'";

and I'm executing this as follows


SqlCeCommand com = new SqlCeCommand(Sqlcommand, conn);
SqlCeDataAdapter da = new SqlCeDataAdapter(com);

after these, just to be sure, I want to check if the query returned some rows or not
what should I do?

note: I've tried these ->

DataSet s = new DataSet();
da.Fill(s);
if( s == null)
if( s.Tables.Count == 0)
if( da == null)

can anybody help? :/