C# LINQ：点符号等效于 JOIN
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LINQ: dot notation equivalent for JOIN
提问by p.campbell
Consider this LINQ expression written using query notation:
考虑使用查询符号编写的这个 LINQ 表达式：
List<Person> pr = (from p in db.Persons
join e in db.PersonExceptions
on p.ID equals e.PersonID
where e.CreatedOn >= fromDate
orderby e.CreatedOn descending
select p)
.ToList();
Question:how would you write this LINQ expression using dot notation?
问题：您将如何使用点表示法编写这个 LINQ 表达式？
采纳答案by Jon Skeet
Like this:
像这样：
List<Person> pr = db.Persons
.Join(db.PersonExceptions,
p => p.ID,
e => e.PersonID,
(p, e) => new { p, e })
.Where(z => z.e.CreatedOn >= fromDate)
.OrderByDescending(z => z.e.CreatedOn)
.Select(z => z.p)
.ToList();
Note how a new anonymous type is introduced to carry both the pand ebits forward. In the specification, query operators which do this use transparent identifiersto indicate the behaviour.
请注意如何引入一个新的匿名类型来向前携带p和e位。在规范中，执行此操作的查询运算符使用透明标识符来指示行为。
