begin
Query.Close;
Query.Sql.Clear;
Query.Sql.Add( 'SELECT COUNT(*) AS TOTAL' );
Query.Sql.Add( 'FROM COUNTRY WHERE CONTINENT = :CONT' );
Query.ParamByName( 'CONT' ).AsString := 'South America';
Query.Open;
ShowMessage( Query.FieldByName( 'TOTAL' ).AsString );
...