public new string ToString() { var ret = $"{FieldName}: "; if (this.ChangeType.HasValue) { if (this.ChangeType == 1) { ret = ret + $"新增:{NewValue}"; } else { ret = ret + $"删除:{OldValue}"; } } else { if (OldValue.IsNullOrWhiteSpace()) { ret = ret + "无"; } else { ret = ret + OldValue; } ret = ret + " 改变为: "; if (NewValue.IsNullOrWhiteSpace()) { ret = ret + "无"; } else { ret = ret + NewValue; } } return(ret); }