## Group by, Count and Lambda Expression怎么理解？内容来源于 Stack Overflow，并遵循CC BY-SA 3.0许可协议进行翻译与使用

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``````SELECT STATE, COUNT(*)
FROM MYTABLE
GROUP BY STATE;
``````

``````public IEnumerable<object> PorcentajeState(Guid id)
{
return _context.Sates.Where(a => a.Id == id)
.GroupBy(a => a.State)
.Select(n => new { n.StateId , n.Count() });
}
``````

### 2 个回答

``````public IEnumerable<object> PorcentajeState(Guid id)
{
return _context.Sates.Where(a => a.Id == id)
.GroupBy(a => a.StateId)
.Select(g => new { g.Key, Count = g.Count() });
}
``````

``````public IEnumerable<object> PorcentajeState(Guid id)
{
return from a in _context.Sates
where a.Id == id
group a by a.StateId into g
select new { a.Key, Count = g.Count() };
}
``````

``````new { StateId = g.Key, Count = g.Count() }
``````

```public IEnumerable<object> PorcentajeState(Guid id)
{
return _context.Sates.Where(a => a.Id == id)
.GroupBy(a => a.StateId)
.Select(g => new { g.Key, Count = g.Count() });
}```

```public IEnumerable<object> PorcentajeState(Guid id)
{
return _context.Sates.Where(a => a.Id == id)
.GroupBy(a => a.StateId)
.Select(g => new { g.Key.StateId, Count = g.Count() });
}```