Help:the opreation with a SQLite3Dataset
lazarus / 16-Databases

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Enigma Huang · 2013-02-23 08:39

I'm a beginner on Database, and I've got some trouble with my
SQLite3Dataset, please help me!

For example, I have a simple table that only with two field "Name" and
"Email" which are all ftString. And now the SQLite3Dataset(for
convenience I will use SQLite3 in the below) is opened. And I want to
operate after located it like

 Code: [Select]  AimID:=StrToInt(Edit1.Text);
  whileSQLite3.RecNo<AimID do
  begin
    SQLite3.Next;
    SQLite3.CursorPosChanged;
  end;

  while SQLite3.RecNo>AimID do
  begin
    SQLite3.Prior;
    SQLite3.CursorPosChanged;
  end;

  with SQLite3 do
  begin
    FieldByName('Name').AsString:=Edit2.Text;
    FieldByName('EMail').AsString:=Edit2.Text;
  end;
But lazarus tells me that the "SQLite3 is not in a edit or insert
state". How can I solve this?

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taazz · 2013-02-23 10:31

with SQLite3 do
  begin
    Edit;
    FieldByName('Name').AsString:=Edit2.Text;
    FieldByName('EMail').AsString:=Edit2.Text;
  end;

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Enigma Huang · 2013-02-23 10:53

Quote from: taazz on February 23, 2013, 11:31:58 am  with SQLite3 do
  begin
    Edit;
    FieldByName('Name').AsString:=Edit2.Text;
    FieldByName('EMail').AsString:=Edit2.Text;
  end;

Thanks a lot ^_^. By the way, do I need to do any other operation
after edit? I mean that whether it will meet a error or exception if I
read or add records or execute other operations just after the edit?

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taazz · 2013-02-23 13:12

after you finish editing the record's data you have to call post to
save the data, and depending the design of SQLite3dataset object you
might also need to call ApplyUpdates to persist the data on the
datafile.

I do not use sqlite and although I think is a superb peace of code the
lack of proper data types and a few other things makes me keep my
distance, that's why I can't tell you for sure what is required.

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snorkel · 2013-03-07 16:06

right after the edit you need to post the data, then in the after post
event of the dataset you need to call
applyupdates and then (whatever you called your
transaction).commitretaining.

You should then also share the event with the after delete event as
well.

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snorkel · 2013-03-07 16:12

if your looping through a dataset you should do it like this:

Code: [Select]while not mydataset.eof do
begin
        if mydataset.fieldbyname('myfieldname').asstring = 'bbdfdf'
then
           begin
                    //do something
           end;
       mydataset.next;
end;

Also if you have a DBgrid attached to the dataset you should to a
beginupdate before you start the loop and a endupdate when you
are done so the dbgrid does not update/scroll while you process the
dataset.