2 question about SQLite
lazarus / 16-Databases

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free07 · 2012-11-22 15:10

Hi all,

Using Free Pascal and XCode, i have two question :

First one :
Here is my code :
Code: [Select]function TAccesBase.GetLibSequence(P_iSequence :
integer; var P_sLibSequence : UnicodeString) : boolean;
var l_bOk : boolean;
{$IFDEF FPC}
    l_sSQL : UnicodeString;
    l_DB : TSQLite;
    l_SL : Classes.TStringList;
{$ENDIF}

begin
  l_bOk := false;
        P_sLibSequence := '';
{$IFDEF FPC}
  try
    l_SL := Classes.TStringList.create;
    l_DB := TSQLite.Create(UnicodeString(pAB_sFileName));
                l_sSQL := 'SELECT Libelle FROM Sequence WHERE
IdSequence = ''' + IntToStr(P_iSequence) + '''';
    l_bOk := l_DB.Query(l_sSQL, l_SL);
    if l_bOk = true then
      P_sLibSequence := l_SL.Text;   // the result is allways :
'Libelle Libx"
    l_bOk := Length(P_sLibSequence) > 0;
    freeandnil(l_DB);
    freeandnil(l_SL);
        except
    on E:Exception do
    begin
      ShowMessage(E.Message);
                        l_bOk := false;
    end;
  end;
{$ENDIF}
        Result := l_bOk;
end;

I get my libelle, every is ok except the string libelle is added
before my libelle , why ?
In fact, he added in first the name of the column, how can i get it
without it ?

2nd Question :

How can i get a blob contains a bitmap, i cannot used DB.Query to
obtain it because the syntax is :
DB.Query(sql : string, result : string)...

Where can i find documentation about TSQLite ?

Sorry it made 3 questions
TIA

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Phil · 2012-11-23 16:58

I'm not aware of any documentation for the TSQLite class. Looking at
the source code copyright it looks like some of the oldest code in
FPC. And it is clunky to use at first.

The query result is a TStringList. The first item is a comma-separated
list of fields identifying the data returned. Each additional item in
the TStringList is a comma-separated list of data - that is, each item
indexed starting with 1 is data record.

In your case, you're returning only a single item and a single record,
so you don't need to parse either the field list or the data list.
Just l_SL[1] is all you need. For multiple fields, use the ValueList
procedure to do the parsing.

I find it useful to use "object composition" to wrap a TSQLite object
in a Pascal class. See the UnicodeDb.pas unit here for an example:

http://web.fastermac.net/~MacPgmr/qxotica/QxoticaStatus.html


Also, you don't need to use UnicodeString. FPC's SQLite units wrap the
UTF8 functions in the SQLite library, not the UTF16 functions.


You can store a bitmap as a hex string in the file and thus query it
as a string.

Thanks.

-Phil

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free07 · 2012-11-23 17:33

Thanks Phil,

Sorry i don't find UnicodeDb.pas ...
Yes, in fact, i need a simple Free Pascal wrapper for the SQLite API.
without configuration and component, just a class that can be used
with SQLite Database.
And with documentation :-)
If anyone knows it ...
TIA

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Phil · 2012-11-23 17:43

Quote from: free07 on November 23, 2012, 06:33:17 pm
Sorry i don't find UnicodeDb.pas ...


http://sourceforge.net/p/qxotica/code/6/tree/trunk/demos/Unicodum/pasc
al_server/UnicodeDb.pas