/// <summary>
/// 更新父级Id实例事务时候新建索引。
/// </summary>
/// <typeparam name="TParentIndex">索引类型。</typeparam>
/// <param name="db">数据库事务操作接口实例。</param>
/// <param name="id">当前实例Id。</param>
/// <param name="parentId">父级Id。</param>
/// <returns>返回添加结果。</returns>
public static bool UpdateIndex <TParentIndex>(this IDbTransactionContext <TParentIndex> db, int id, int parentId)
where TParentIndex : IParentIndex, new()
{
db.Delete(x => x.Id == id);//删除原有的父级ID
return(db.CreateIndex(id, parentId));
}