Talk:Lazarus Database Overview

Hi,

I would like to change some code given in the MySQL example for Lazarus. I think there are some fundamental errors here. For instance

procedure ShowString (S : string);
(* display a string in a Memo box *)
begin
       trymysqlForm1.ResultsMemo.Lines.Add (S)
end;

should be done in a methode of the form like:

procedure TtrymysqlForm1.ShowString (S : string);
(* display a string in a Memo box *)
begin
       ResultsMemo.Lines.Add (S)
end;

It makes the use of the trymysqlForm1 variable obsolete, which might be the cause of runtime errors. Well to cut a long story short, I would like the code to be changed into:

procedure TFormTryMySQL.QueryButtonClick(Sender: TObject); var

 tableBuffer: PMYSQL_RES;
 recordBuffer: TMYSQL_ROW;
 fieldList: TStringList;
 I: Integer;
 stMessage: String;

begin

 // Show how we can get records from a table
 StatusBar1.SimpleText := 'Executing query: ' + CommandEdit.Text;
 ShowString('Executing query: ' + CommandEdit.Text);
 if (mysql_query(mySQLSock, PChar(CommandEdit.Text)) < 0) then begin
   ShowString('Query failed '+ StrPas(mysql_error(mySQLSock)));
 end else begin
   tableBuffer := mysql_store_result(mySQLSock);
   try
     if tableBuffer = nil then begin
       ShowString('Query didnot return any results.');
     end else begin
       fieldList := TStringList.Create;
       try
         ShowString('Number of records returned  : ' + IntToStr(mysql_num_rows(tableBuffer)));
         ShowString('Number of fields per record : ' + IntToStr(mysql_num_fields(tableBuffer)));
         // Lets get a list a returned fields.
         for I := 0 to pred(mysql_num_fields(tableBuffer)) do begin
           fieldList.Add(mysql_fetch_field_direct(tableBuffer, I).name);
         end;
         recordBuffer := mysql_fetch_row(tableBuffer);
         while (recordBuffer <> nil) do begin
           stMessage := ;
           for I := 0 to pred(mysql_num_fields(tableBuffer)) do begin
             stMessage := stMessage + fieldList[I] + ': ' + recordBuffer[I] + ', ';
           end;
           Delete(stMessage, Length(stMessage) - 2, 2);
           ShowString(stMessage);
           recordBuffer := mysql_fetch_row(tableBuffer);
         end;
       finally
         fieldList.Free;
       end;
     end;
   finally
     // Free the results, thus saving resources.
     mysql_free_result(tableBuffer);
   end;
 end;

end;

There are some more changes, in fact I expanded it with a second form to show data in a ListView. So if there is any interest in that I'm willing to contribute it to the documentation project.