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  • linq 日常关键字使用

    1.from

    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;
    

     3.select 

    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];

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  • 原文地址:https://www.cnblogs.com/lijiasnong/p/6133457.html
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