Get data in database through SqlDataAdapter (C#)

String ConnStr = "Data Source=localhost;Initial Catalog=abc;User ID=sa;Password='pw';";
String SQL = "SELECT ID, FirstName FROM Employee "
+ "WHERE ID IS NOT NULL";
SqlDataAdapter TitlesAdpt = new SqlDataAdapter SQL, ConnStr);
DataSet Titles = new DataSet();
// No need to open or close the connection
// since the SqlDataAdapter will do this automatically.
TitlesAdpt.Fill(Titles);