[英]Order by, distinct and select top 5 results with linq
大家好,我正在尝试 select 来自数据库的 5 条不同记录,但我需要有序且不同。 我正在寻找最有效的方法。 问题是 Distinct() 方法打乱了排序,所以我试图通过对它们进行分组来实现它,但似乎分组也打乱了排序。 也许有人会有一个好的解决方案?
这是我目前的尝试。
public async Task<List<RecentProjectDto>> GetMostRecentProjects(int userId, int companyId)
{
using (var db = _dbFactory.Create())
{
var recentProjects = await db.ScheduleLogs
.OfType<WorkLog>()
.Where(x => x.UserId == userId)
.Where(x => x.User.CompanyId == companyId)
.OrderByDescending(x => x.End)
.GroupBy(x => new { x.ProjectId, x.Project.Name, x.Project.Key, x.Project.Colour })
.Select(x => new RecentProjectDto
{
ProjectId = x.ProjectId,
ProjectName = x.Project.Name,
ProjectKey = x.Project.Key,
Colour = x.Project.Colour
})
.Take(5)
.ToListAsync();
return recentProjects;
}
}
这样的事情有用吗?
var recentProjects = await db.ScheduleLogs
.OfType<WorkLog>()
.Where(x => x.UserId == userId)
.Where(x => x.User.CompanyId == companyId)
.GroupBy(x => new { x.ProjectId, x.Project.Name, x.Project.Key, x.Project.Colour })
.OrderByDescending(x => x.Max(a=>a.OrderDate))
.Select(x => new RecentProjectDto
{
ProjectId = x.Key.ProjectId,
ProjectName = x.Key.Name,
ProjectKey = x.Key.Key,
Colour = x.Key.Colour
})
.Take(5)
.ToListAsync();
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