Question

Recently I met a strange problem, see code snips as below:

var
  sqlCommand: string;
  connection: TADOConnection;
  qry: TADOQuery;
begin
  connection := TADOConnection.Create(nil);
  try
    connection.ConnectionString := 'Provider=Microsoft.Jet.OLEDB.4.0;Data Source=Test.MDB;Persist Security Info=False';
    connection.Open();
    qry := TADOQuery.Create(nil);
    try
      qry.Connection := connection;
      qry.SQL.Text := 'Select * from aaa';
      qry.Open;

      qry.Append;
      qry.FieldByName('TestField1').AsString := 'test';

      qry.Post;
      beep;
    finally
      qry.Free;
    end;
  finally
    connection.Free;
  end;
end;

First, Create a new access database named test.mdb and put it under the directory of this test project, we can create a new table named aaa in it which has only one text type field named TestField1.

We set a breakpoint at line of “beep”, then lunch the test application under ide debug mode, when ide stops at the breakpoint line (qry.post has been executed), at this time we use microsoft access to open test.mdb and open table aaa you will find there are no any changes in table aaa, if you let the ide continue running after pressing f9 you can find a new record is inserted in to table aaa, but if you press ctrl+f2 to terminate the application at the breakpoint, you will find the table aaa has no record been inserted, but in normal circumstance, a new record should be inserted in to the table aaa after qry.post executed.
who can explain this problem , it troubles me so long time. thanks !!!

BTW, the ide is delphi 2010, and the access mdb file is created by microsoft access 2007 under windows 7

Answer 1

Marjan, thanks for your response again, but i can’t accept this behaviour what the connection enginee processes, today I find something useful on MSDN website, see:

http://msdn.microsoft.com/en-us/library/ms719649(v=VS.85).aspx

I have resolved the problem fortunately according to the article, Actually, the default value of the property “Jet OLEDB:Implicit Commit Sync” is false, According to the explanation of this property, Be false implies that the implicit transaction will use asynchronouse mode. so what we can do is set this property be true by using code snips as below :

connection.Properties.Item['Jet OLEDB:Implicit Commit Sync'].Value := true;

BTW, according to that article, this property can only be set by using the Properties property of the connection object, otherwise if it is set in connection string, an error will occur