Question

These are my two tables. How can i make LINQ query between two tables :

(1) Users : 
       Id , Name, Email
(2) Articles : 
       Id,Title, Description ,UserId (Foreign key reference to User Table Id column)

Questions :

(1)  How to select all records that are similar in both tables ? (Inner Join)
(2)  Left Join (Only record of left table)
(3)  Right Join (Only record of right table)
(4)  Full outer join (All records of both tables)

请帮我创建带有连接的LINQ查询，因为我是LINQ to SQL的初学者。

Answer 1

以下是所有伪代码，您需要根据您的桌面名称和需求进行调整。

 var question_one = (from u in Users
                        join a in Articles on u.Id equals a.UserId)

var question_two = (from u in user
                    join a in Articles on u.Id equals a.UserId into leftJoin
                    from subUser in leftJoin.DefaultIfEmpty()
                    select subUser)

var question_three = (from a in Articles
                    join  u in user  on a.UserId equals u.Id  into leftJoin
                    from subUser in leftJoin.DefaultIfEmpty()
                    select subUser)

问题四无法在传统的外连接中完成，因为，articles表实际上是用户的子表。因此，任何文章都保证始终拥有用户。你可以做的就是用你的用户表进行电子化，并包括任何类似的文章

警告伪代码，因为我不知道您的导航属性

Users.include(x => x.Articles).ToList();

msdn for linq joining

复杂的LINQ查询

1 个答案: