linq 日常关键字使用

var scoreQuery = from student in students
from score in student.Scores
where score > 90
select new { Last = student.LastName, score };
2.where

var queryLowNums3 =
from num in numbers
where num < 5
where num % 2 == 0
select num;

var studentQuery7 =
from student in app.students
where student.ID > 111
select new { student.First, student.Last };
4.group

var studentQuery =
from student in students
let avg = (int)student.Scores.Average()
group student by (avg == 0 ? 0 : avg / 10) into g
orderby g.Key
select g;
5.into

var wordGroups1 =
from w in words
group w by w[0] into fruitGroup
where fruitGroup.Count() >= 2
select new { FirstLetter = fruitGroup.Key, Words = fruitGroup.Count() };
6.orderby

var sortedGroups =
from student in students
orderby student.Last, student.First
group student by student.Last[0] into newGroup
orderby newGroup.Key
select newGroup;
7.join

var innerJoinQuery =
from category in categories
join prod in products on category.ID equals prod.CategoryID
select new { ProductName = prod.Name, Category = category.Name }; //produces flat sequence

var innerGroupJoinQuery =
from category in categories
join prod in products on category.ID equals prod.CategoryID into prodGroup
select new { CategoryName = category.Name, Products = prodGroup };
8.ascending

IEnumerable<string> sortAscendingQuery =
from vegetable in vegetables
orderby vegetable ascending
select vegetable;
9.descending

IEnumerable<string> sortDescendingQuery =
from vegetable in vegetables
orderby vegetable descending
select vegetable;
10.on

var innerJoinQuery =
from category in categories
join prod in products on category.ID equals prod.CategoryID
select new { ProductName = prod.Name, Category = category.Name };
11.equals

var innerJoinQuery =
from category in categories
join prod in products on category.ID equals prod.CategoryID
select new { ProductName = prod.Name, Category = category.Name };
12.by

var query = from student in students
group student by student.LastName[0];