Sqlite XE4 iOS

[isysoftware]

Hi All.

I have this code for an application in Delphi XE4 for iOS with a Sqlite Database.
If I execute my app on Windows, it works.
Deployng it on a real iPAD, it don't work.

Code: Select all

function DeterminaID_Generico_a(aConnection: TUniConnection; aTable, aKey: string; aowner: TComponent):integer;
var aDs:TUniQuery; aNum:integer;
begin
     aDs:=TUniQuery.Create(aowner);
     with aDs do
        begin
          connection:=aConnection;
          active:=False;
          sql.Clear;
          SQL.add('SELECT max('+aKey+') as mymax FROM '+aTable);
          active:=True;
        end;
     if(aDs.RecordCount > 0) then
        begin
          if(aDs.FieldValues['mymax'] = null) then
             result:=1
          else
             begin
                 aNum:=aDs.FieldByName('mymax').asinteger;
                 result:=aNum+1;
             end;
        end
     else
         result:=1;
end;

This code don't work: why? Can you help me?
Thanks

[AlexP]

Hello,

We have already fixed the problem, this fix will be added to the next UniDAC version.

[isysoftware]

Hi Alex, thanks for your reply.
When do you think that the fix will be released?

[AlexP]

Hello,

We plan to release a new version in the next month.

[isysoftware]

Next month???

We couldn't have a patch at this moment?

[AlexP]

Hello,

Please send us your license number and e-mail to alexp*devart*com in order for me to send you the fixed version of UniDAC.

[isysoftware]

Hi Alex,
yesterday I have sent you an E-Mail.
I have received a link to download Unidac: I have installed it, but I have the same problem. Maybe It isn'n the last version of Unidac whit fix

[AlexP]

hello,

I sent you a fixed version on July 13

[isysoftware]

Hi Alex,
Thanks for your reply: now problem is fixed and Max function works on ipad.

I have a question:
if a table is empty, Max Function Return ' " ' (double quote) else return a value (integer ).
In my code I check if Max's returnerd value is NULL or not.
There is a problem if I change my code to check if returned value is = '': if table is empty, there isn't any problem; but if table has record, in IF statement there will be an AV on converting string '' in integer.

Have you any ideas?

Thanks

[AlexP]

Hello,

To check the field for a Null value, you can use the IsNull property of this field, for example:

LiteConnection1.ExecSQL('CREATE TABLE TEST(ID INTEGER)');
LiteQuery1.SQL.Text := 'SELECT MAX(ID) as ID FROM TEST';
LiteQuery1.Open;
if not LiteQuery1.Fields[0].IsNull then
ShowMessage(IntToStr(LiteQuery1.Fields[0].AsInteger));

[isysoftware]

Hi Alex,
the same problem is now on XE5 whit SQLite in Windows.
For iOS I haven't problem, but whit windows yes.

[AlexP]

If you mean, that an empty string is returned when DataSet is empty, when using aggregating functions, then this behavior is similar for every platform, and you should use the Fields.isnull method to check data existence. There is no more errors when executing your code.

[isysoftware]

Yes, I mean this.
Ok, I can use isNull, and it works, but for iOS I haven't this problem.

Thanks,
Flavio

[AlexP]

On both operation systems (win32 and iOS), the error occurs at the line "aDs.FieldByName('mymax').asinteger" on an attempt to map an empty string to Integer. If you have another error, please provide the error message text and the line where it occurs.

[isysoftware]

This is the code that I'm using: in iOS it works and in Windows no.

Code: Select all

 aDs:=TUniQuery.Create(aOwner);
     with aDs do
        begin
          connection:=aConnection;
          active:=False;
          SQL.add('Select Max('+aKey+') as Massimo From '+LowerCase(aTable));
          active:=True;
        end;
     if((aDs.RecordCount>0)) then
        begin
          if(aDs.FieldValues['Massimo'] = null) then
             result:=1
          else
             begin
                 aNum:=aDs.FieldValues['Massimo'];
                 result:=aNum+1;
             end;
        end
     else
         result:=1;