Seleccionar caso en LINQ [duplicar]
Esta pregunta ya tiene una respuesta aquí:
- linq case statement 7 respuestas
¿Cómo puedo traducir esto a LINQ?
select t.age as AgeRange, count(*) as Users
from (
select case
when age between 0 and 9 then ' 0-25'
when age between 10 and 14 then '26-40'
when age between 20 and 49 then '60-100'
else '50+' end as age
from user) t
group by t.age
¡Gracias!
26
Author: abatishchev, 2010-11-22
5 answers
Tal vez esto funcione:
from u in users
let range = (u.Age >= 0 && u.Age < 10 ? "0-25" :
u.Age >= 10 && u.Age < 15 ? "26-40" :
u.Age >= 15 && u.Age < 50 ? "60-100" :
"50+")
group u by range into g
select new { g.Key, Count=g.Count() };
39
Author: Botz3000,
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2010-11-22 09:57:31
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2010-11-22 09:57:31
var query = from grade in sc.StudentGrade
join student in sc.Person on grade.Person.PersonID
equals student.PersonID
select new
{
FirstName = student.FirstName,
LastName = student.LastName,
Grade = grade.Grade.Value >= 4 ? "A" :
grade.Grade.Value >= 3 ? "B" :
grade.Grade.Value >= 2 ? "C" :
grade.Grade.Value != null ? "D" : "-"
};
11
Author: Pranay Rana,
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2010-11-22 10:02:13
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2010-11-22 10:02:13
Usa algo así:
class AgeHelper
{
private static Dictionary<IEnumerable<int>, string> dic = new Dictionary<IEnumerable<int>, string>
{
{ Enumerable.Range(0, 10), "0-25" },
{ Enumerable.Range(10, 5), "26-40" },
{ Enumerable.Range(15, 35), "60-100" }
};
public string this[int age]
{
get
{
return dic.FirstOrDefault(p => p.Key.Contains(age)).Value ?? "50+";
}
}
}
El resto de la respuesta de @Botz3000:
from u in users
let range = new AgeHelper()[u.Age]
...
7
Author: abatishchev,
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2010-11-22 10:16:45
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2010-11-22 10:16:45
¿Algo así?
var users = (from u in Users
select new
{
User = u,
AgeRange =
u.Age >= 0 && u.Age <= 9 ? "0-25" :
u.Age <= 14 ? "26-50" :
u.Age <= 49 ? "60-100":
"50+"
}).GroupBy(e => e.AgeRange);
4
Author: Martin Doms,
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2010-11-22 09:55:39
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/ajaxhispano.com/template/agent.layouts/content.php on line 61
2010-11-22 09:55:39
No conozco ninguna manera de crear SQL eficiente como este, usando una instrucción LINQ. Pero puedes usar:
- Utilice un procedimiento almacenado (o función), y llame al procedimiento almacenado desde LINQ.
- Usar SQL directo
Seguro que puedes usar muchas sentencias condicionales en línea (? :
), pero no creo que el resultado sea eficiente.
0
Author: GvS,
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2010-11-22 09:48:34
Warning: date(): Invalid date.timezone value 'Europe/Kyiv', we selected the timezone 'UTC' for now. in /var/www/agent_stack/data/www/ajaxhispano.com/template/agent.layouts/content.php on line 61
2010-11-22 09:48:34