/// <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>
/// <param name="cancellationToken">取消标志。</param>
/// <returns>返回添加结果。</returns>
public static async Task <bool> UpdateIndexAsync <TParentIndex>(this IDbTransactionContext <TParentIndex> db, int id, int parentId, CancellationToken cancellationToken = default)
where TParentIndex : IParentIndex, new()
{
await db.DeleteAsync(x => x.Id == id, cancellationToken);//删除原有的父级ID
return(await db.CreateIndexAsync(id, parentId, cancellationToken));
}