//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;