[英]LINQ, double join with count and orderby
LINQ新手在查询中挣扎,这在常规SQL中非常容易,但是由于某种原因,在尝试使用lambda / query进行表达时,我感到非常痛苦。
我有三个对象:组织
public class Organization
{
public int OrganizationId { get; set; }
public ICollection<Employee> Employees { get; set; }
}
雇员
public class Employee
{
public int EmployeeId { get; set; }
public Organization Organization { get; set; }
public ICollection<Ticket> Tickets { get; set; }
}
票
public class Ticket
{
public int TicketId { get; set; }
public Employee Employee { get; set; }
}
使用LINQ,我需要按组织的票证数量来检索组织的有序列表,作为IQueryable,它是可取的。
到目前为止,这是我想出的:
var q = Organizations.Join
(
Employees,
org => org.OrganizationId,
emp => emp.Organization.OrganizationId,
(org, emp) => new {org, emp}
)
.Join
(
Tickets,
t => t.emp.EmployeeId,
ticket => ticket.Employee.EmployeeId,
(t, ticket) => new {t, ticket}
)
.GroupBy(t => t.t.org.OrganizationId)
.Select
(
t => new { OrganizationId = t.Key, TCount = t.Count() }
)
.OrderByDescending(t => t.TCount).Dump()
所以我有组织的ID和数量。 我将如何检索整个组织对象?
您不需要使用join,因为每个类都有集合。
Organizations.OrderByDescending(o => o.Employees.Sum(e => e.Tickets.Count()));
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