mysql + unidac 使用事务例子

//备注：mysql必须是使用innoDB引擎才支持事务功能，否则以下事务相关代码将失效。//SQL SERVER和Oracle还没试，明天回公司试了再发代码。procedure TForm1.btn1Click(Sender: TObject);
var
  i, j: Integer;
begin
  UniConnection1.Connect;
  try
    try
      UniTransaction1.Connections[0].StartTransaction;
      UniQuery1.Params.Clear;
      UniQuery1.SQL.Text := 'insert into user (username,password)values(:username, :password)';
      UniQuery1.Params.ParamByName('username').Value := 'eboy';
      UniQuery1.Params.ParamByName('password').Value := '1111';
      UniQuery1.ExecSQL; //如果不使用事务，这条将插入进去

      UniQuery1.Params.Clear;
      UniQuery1.SQL.Text := 'insert into user (username,password)values(:username, :password)';
      UniQuery1.Params.ParamByName('username').Value := 'frr';
      UniQuery1.Params.ParamByName('password').Value := '123';
      UniQuery1.ExecSQL; //如果不使用事务，这条将插入进去

      UniQuery1.Params.Clear;
      UniQuery1.SQL.Text := 'insert into user (username,password)values(:username, :password)';
      UniQuery1.Params.ParamByName('username').Value := 'lj';
      UniQuery1.Params.ParamByName('password').Value := '880414';
      UniQuery1.ExecSQL; //如果不使用事务，这条将插入进去

      UniQuery1.Params.Clear;
      UniQuery1.SQL.Text := 'insert into user (username,password)values(:username, :password)';
      UniQuery1.Params.ParamByName('username').Value := 'lj';
      UniQuery1.Params.ParamByName('password').IsNull; //字段设为not null，所以这里会出错
      UniQuery1.ExecSQL; //开启事务后，上面的三条都将回滚
      
      UniTransaction1.Connections[0].Commit;

    except on e: Exception do
      begin
        UniTransaction1.Connections[0].Rollback;
        ShowMessage(e.Message);
      end;
    end;  
  finally
    UniConnection1.Disconnect;
  end;
end;