ftAutoinc in Memdataset
lazarus / 16-Databases

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P.curtis · 2020-05-01 06:47

How can I use ftAutoinc in MemDataset?

I am used to Autoinc in MariaDB where the result, as integer, is
incremented per record, I would like the same in MemDataset.

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wp · 2020-05-01 07:08

AFAIK, TMemDataset is very simply and does not support AutoInc. Try
TBufDataset instead, it is more complete.

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P.curtis · 2020-05-01 08:15

Cant get my head round it. I have attached a small demo program could
someone have a look at whats wrong

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wp · 2020-05-01 08:26

Create the fields at runtime. Designtime code still seems to be
buggy...
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormCreate(Sender: TObject);begin  with BufDataset1 do begin  
FieldDefs.Clear;    FieldDefs.Add('fnIDX', ftAutoInc);   
FieldDefs.Add('fnDATA', ftString, 10);    CreateDataset;  end;end;

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P.curtis · 2020-05-01 08:47

OK. That works, thanks, but creates a new question. When I dynamically
create my fields how can I specify presicion for ftFloat fields?

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wp · 2020-05-01 09:03

TFieldDefs also has method AddFieldDef which returns the created
FieldDef so that you can access all properties. A bit more typing,
though, or create your own function for it:

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TForm1.FormCreate(Sender: TObject);begin  with BufDataset1 do begin  
FieldDefs.Clear;    with FieldDefs.AddFieldDef do    begin      Name
:= 'fnIDX';      DataType := ftAutoInc;    end;    with
FieldDefs.AddFieldDef do    begin      Name := 'fnDATA';      DataType
:= ftString;      Size := 10;    end;    with FieldDefs.AddFieldDef
do    begin      Name := 'fnFLOAT';      DataType := ftFloat;     
Precision := 3;    end;    CreateDataset;  end;end;

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P.curtis · 2020-05-01 09:06

Job done. Thanks.