我如何将此 SQL 转换为 Entity Framework LINQ 查询

Question

谁能帮我把这个 SQL 查询转换成 EntityFramework LINQ？

DECLARE @UserId varchar(50) = '123'
SELECT
   TL.TrackId, 
   COUNT(*) AS LikeCount,
   (SELECT IIF(COUNT(*) > 0, 'true','false') FROM UserTrackLikes WHERE
    UserId = @UserId AND TrackId = TL.TrackId) AS IsLiked
FROM TrackList AS TL
LEFT OUTER JOIN UserTrackLikes AS UTL 
ON UTL.TrackId = TL.TrackId
GROUP BY TL.TrackId

Answer 1

您可以使用查询语法：

int userId = 123;
var result = (from trackList in context.TrackLists
              select new 
              {
                 trackList.TrackId,
                 LikeCount = trackList.Likes.Count(),
                 IsLiked = trackList.Likes.Any(x => x.UserId == userId)
              }).ToList();

假设这里Likes是UserTrackLike的集合，声明如下：

public ICollection<UserTrackLike> Likes { get; set; }

我如何将此 SQL 转换为 Entity Framework LINQ 查询

How do i convert this SQL to Entity Framework LINQ query

.net

sql

linq

c#-4.0

entity-framework-6