用sql + Ado设置access的字段的默认值

procedure TFormLOrder.ModifyDB; var F: Integer; begin with TADOQuery.Create( nil ) do try // ConnectionString := GetAdoAccConStr(SoftPath + SendDataDir +LogisOrderDB); Connection := ADOCon; SQL.Add( ' Select * from ' + tblogistics_orders);

procedure TFormLOrder.ModifyDB;
var
  F: Integer;
begin
  with TADOQuery.Create(nil) do
  try
//    ConnectionString := GetAdoAccConStr(SoftPath + SendDataDir +LogisOrderDB);
    Connection := ADOCon;
    SQL.Add('Select * from ' + tblogistics_orders); //不能用 Select seller_flag from ，否则会报 参数 seller_flag 没有默认值
    Open;
    if FieldList.Find('seller_flag') = nil then //不能用 FieldByName,因为参数必须是存在的字段，否则会产生异常
    begin
      Close;
      SQL.Clear;
      SQL.Add('ALTER TABLE ' + tblogistics_orders);
      SQL.Add('ADD COLUMN seller_flag INTEGER DEFAULT 0');
//      ADOCon.Execute(sql.Text, F); //这个也可以的，并 不是 必须用这个
      ExecSQL;
    end;
    //
    Close;
    sql.Clear;
    sql.Add('Select sub_tids from ' + tblogistics_orders);
    Open;
    if (FieldCount > 0) and (FieldByName('sub_tids').Size 255