我有一个表格作为
学生姓名/教室/A 年级/B 年级/C 年级/年级日期
学生的教室是固定的,因此列永远不会改变。
每个学生都有多个具有不同年级日期的 A、B 级和 C 级值。
public virtual IList<ClassroomDetail> GetLatestClassroomDetail(string classroom)
{
var query = from pc in _classroomDetailRepository.Table
where pc.Classroom == classroom
select pc;
var result = new List<ClassroomDetail>(query);
return result;
}
上面的查询返回所有内容,并且列表中有多个相同的学生。
如何仅获取最新值?
表:
课堂大师
- 编号
- 更新日期
- 课堂
教室详情
- 编号
- Cm_Id(具有带有 ClassroomMaster ID 的外键(
- 学生姓名
- A级
- B级
- C级
- 成绩日期
在控制器上
var bdetail = _classroomService.GetLatestClassroomDetail(classroom).OrderBy(d => d.StudentName);
var model = new List<ClassroomDetail>();
foreach (var pr in bdetail)
{
model.Add(new ClassroomDetail
{
Id = pr.Id,
Classroom = pr.Classroom,
StudentName = pr.StudentName,
GradeA = pr.GradeA,
GradeB = pr.GradeB,
GradeC = pr.GradeC,
GradeDate = pr.GradeDate,
});
}
return PartialView(model);
它将解决您的问题
var query = _classroomDetailRepository.Table
.Where(a => a.Classroom == classroom)
.Select(b => b.OrderByDescending(y => y.GradeDate).Take(1).FirstOrDefault());
我终于找到了解决方案:D
public virtual IList<ClassroomDetail> GetLatestClassroomDetail(string classroom)
{
var query = _classroomDetailRepository.Table
.Where(z => z.Classroom == classroom)
.GroupBy(x => x.StudentName)
.Select(x => x.OrderByDescending(y => y.GradeDate).Take(1).FirstOrDefault());
var result = new List<BunkerPriceDetail>(query);
return result;
}