/// <summary>
        /// 拷贝构造函数
        /// </summary>
        /// <param name="toCopy">To copy.</param>
        public RowPutChange(RowPutChange toCopy) : base(toCopy.TableName, toCopy.GetPrimaryKey())
        {
            if (toCopy.timestamp.HasValue)
            {
                timestamp = toCopy.timestamp;
            }

            columnsToPut.AddRange(toCopy.columnsToPut);
        }