LINQ-分组后使用聚合函数
发布时间:2020-12-14 05:05:47 所属栏目:百科 来源:网络整理
导读:1 .实现代码 /// summary /// 获取指定课程编号的总时长 /// /summary /// param name="courseId" 课程编号 /param /// returns/returns public async Task decimal GetTotalDurationByCourseId( int courseId) { decimal totalDuration = 0 ; var result =
1.实现代码
/// <summary> /// 获取指定课程编号的总时长 /// </summary> /// <param name="courseId">课程编号</param> /// <returns></returns> public async Task<decimal> GetTotalDurationByCourseId(int courseId) { decimal totalDuration = 0; var result = _sectionInfoRepository.GetAll().AsNoTracking().Where(x => x.CourseId == courseId) .GroupBy(x => new { x.CourseId }) .Select(g => new { TotalDuration = g.Sum(x => x.ResourceDuration) }).FirstOrDefault(); var r = result.GetType().GetProperty("TotalDuration"); if (r != null) { totalDuration = Convert.ToDecimal(r.GetValue(result,null)); } return await Task.FromResult(totalDuration); } (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |