/// <summary>
/// 添加排序子句
/// </summary>
/// <param name="field"></param>
/// <param name="order"></param>
public void AddOrderBy(string field, Sorting order)
{
OrderByClause NewOrderByClause = new OrderByClause(field, order);
_orderByStatement.Add(NewOrderByClause);
}
/// <summary>
/// 添加排序子句
/// </summary>
/// <param name="clause"></param>
public void AddOrderBy(OrderByClause clause)
{
_orderByStatement.Add(clause);
}