C# 实体框架4.1统计相同的数据库行 我的设置

我有两个类，这里显示的是本例所需的内容：

public class Photo : Entity
{
    [Key]
    public int Id { get; set; }

    public virtual ICollection<Tag> Tags { get; set; }

    public Photo()
    {
        Tags = new List<Tag>();
    }
}


public class Tag : Entity
{
    [Key]
    public string Text { get; set; }

    public virtual ICollection<Photo> Photos { get; set; }

    public Tag()
    {
        Photos = new List<Photo>();
    }
}

EF/LINQ等效值是多少

第二个问题

---

如何获取每个标签的计数或50个最常用标签的计数？

按标签计数：

from t in Context.Tags
select new
{
    t.Text,
    t.Photos.Count()
}

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).FirstOrDefault()

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).Take(50)

foreach(var result in Context.Tags.Select(x => new { t.Text, t.Photos.Count() }))
{
    Console.WriteLine(string.Format("Text: {0}, Count: {1}", result.Text, result.Count.ToString());
}

最常用的标签：

from t in Context.Tags
select new
{
    t.Text,
    t.Photos.Count()
}

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).FirstOrDefault()

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).Take(50)

foreach(var result in Context.Tags.Select(x => new { t.Text, t.Photos.Count() }))
{
    Console.WriteLine(string.Format("Text: {0}, Count: {1}", result.Text, result.Count.ToString());
}

50个最常用的标签（实际上可能没有50个）：

from t in Context.Tags
select new
{
    t.Text,
    t.Photos.Count()
}

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).FirstOrDefault()

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).Take(50)

foreach(var result in Context.Tags.Select(x => new { t.Text, t.Photos.Count() }))
{
    Console.WriteLine(string.Format("Text: {0}, Count: {1}", result.Text, result.Count.ToString());
}

写意，所以可能不是100%语法正确，也不是最小/最可读的方式

编辑：添加示例：

from t in Context.Tags
select new
{
    t.Text,
    t.Photos.Count()
}

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).FirstOrDefault()

(from t in Context.Tags
let photoCount = t.Photos.Count()
orderby photoCount descending
select new
{
    t.Text,
    photoCount
}).Take(50)

foreach(var result in Context.Tags.Select(x => new { t.Text, t.Photos.Count() }))
{
    Console.WriteLine(string.Format("Text: {0}, Count: {1}", result.Text, result.Count.ToString());
}

---

谢谢，看起来不错。你能用一个例子来进一步说明如何循环所有找到的标记及其计数吗？非常好！有没有更简单的方法只获取最低的标签计数和最高的标签计数？您只需要数字吗？或者你想要数字和标签文本吗？算出了：

intmincount=result.Min（x=>x.Count）。