如何将SQL转成LINQ或其他方法

Question

所以我一直在尝试执行查询。这是查询：


WITH ranked_loggings AS( 
    SELECT m.*, ROW_NUMBER() OVER(PARTITION BY proportioning_dbid ORDER BY logging_dbid DESC) AS rn
    FROM logging AS m ) 
SELECT* FROM ranked_loggings WHERE rn = 1;

我试过很多解决方案，比如 http://www.sqltolinq.com/ and http://www.linqpad.net/。不幸的是，据我所知，这些不支持 PostgreSQL。现在我尝试原始执行查询。现在我无法获得结果并且我的应用程序不断崩溃。有人可以指出我正确的方向还是我在这里完全遗漏了什么？

Answer 1

想通了。显然不可能在没有参数的情况下使用原始 SQL 。是这样解决的：

using (var context = new AmadeusDBContext())
            {
                ICollection<Logging> loggings = context.Loggings
                                    .FromSqlRaw("WITH ranked_loggings AS( " +
                                    "SELECT m.*, ROW_NUMBER() OVER(PARTITION BY proportioning_dbid ORDER BY logging_dbid DESC) AS rn " +
                                    "FROM logging AS m ) " +
                                    "SELECT* FROM ranked_loggings WHERE rn = 1;", new NpgsqlParameter("@parameterrequired", 01))
                                    .ToList<Logging>();

                return loggings;
            }

Answer 2

EF Core 应从此 LINQ 查询生成所需的结果：

var loggings = context.Loggings;

var query =
    from d in loggings.Select(m => new { m.proportioning_dbid }).Distinct()
    from m in loggings
        .Where(m => m.proportioning_dbid == d.proportioning_dbid)
        .OrderByDescending(m => m.logging_dbid)
        .Take(1)
    select m;

如何将SQL转成LINQ或其他方法

How to transfer SQL to LINQ or other methods

sql

linq

postgresql

entity-framework