如何從 EF 中的多個表中查詢數據？

Question

這是我的查詢，用於從 SQL 服務器的多個表中獲取數據

SELECT
    Blob.transactionId,
    Blob.status,
    COUNT(Bsp._id) AS processed,
    Blob.total, 
    Blob.reason,
    (SELECT MAX(MyMaxName) 
     FROM (VALUES 
               (MAX(Fail.ProcessTime)), 
               (MAX(Bsp.ProcessTime)) 
          ) MyAlias(MyMaxName)) AS ProcessTime ,
    COUNT(DISTINCT Fail.id) AS failed
FROM 
    BlobStatus AS Blob
LEFT JOIN 
    BspResponse AS Bsp ON Bsp.tid = Blob.transactionId
LEFT JOIN 
    FailedResponse AS Fail ON Fail.transactionId = Blob.transactionId
WHERE 
    Blob.transactionId = "084f4b75-c38e-449c-a9eb-148dce67111a"
GROUP BY 
    Blob.transactionId, Blob.status, Blob.total, Blob.reason, Blob.failed

在 .NET 代碼中，我通過調用下面提到的方法來嘗試這種方式。 通過參考本教程https://www.entityframeworktutorial.net/Querying-with-EDM.aspx 。 實體 SQL

public BlobResponse GetBlobDetailsById(string tid)
{
        try
        {
            string sqlQuery = $"SELECT  " +
                "  Blob.transactionId, Blob.status,   " +
                "COUNT(Bsp._id) AS processed,  Blob.total,   " +
                " Blob.reason, " +
                "(SELECT" +
                  " MAX(MyMaxName) " +
                  "FROM(VALUES " +
                  $"(MAX(Fail.ProcessTime))," +
                  $" (MAX(Bsp.ProcessTime)) ) " +
                  "MyAlias(MyMaxName)" +
                ") as ProcessTime, " +
                "COUNT(DISTINCT Fail.id) AS failed  " +
                "FROM BlobStatus AS Blob                 " +
                "LEFT JOIN BspResponse AS Bsp ON Bsp.tid = Blob.transactionId   " +
                "LEFT JOIN FailedResponse AS Fail ON Fail.transactionId = Blob.transactionId " +
                $"WHERE Blob.transactionId = {tid} " +
                " GROUP BY Blob.transactionId, Blob.status, Blob.total, Blob.reason, Blob.failed";

            var objctx = ((IObjectContextAdapter)_mriDbContext).ObjectContext;
   
            ObjectQuery<BlobResponse> res = objctx.CreateQuery<BlobResponse>(sqlQuery);
            BlobResponse blobResponse = res.First<BlobResponse>();

            return blobResponse;
        }
        catch (Exception e)
        {
            _logger.LogInformation(e.Message);
            return null;
        }
    }

我收到以下錯誤

[17:27:43 INF] 無法將類型為“Flash.MultiRecordInquiry.Subscriber.Models.Context.MriDbContext”的 object 轉換為類型“System.Data.Entity.Infrastructure.IObjectContextAdapter”。

這是數據庫上下文

public class MriDbContext : DbContext
{
    public MriDbContext(DbContextOptions<MriDbContext> options) : base(options)
    { }

    public DbSet<BSPReponse> BspResponse { get; set; }
    public DbSet<BspStatusDetails> BspStatusDetails { get; set; }
    public DbSet<FhaStatusDetails> FhaStatus { get; set; }

    public DbSet<BlobStatus> BlobStatus { get; set; }

    public DbSet<FailedResponse> FailedResponses { get; set; }
}

我是 EF 新手，不熟悉在實體框架中運行如此復雜的查詢。 請幫助我如何解決此問題

提前致謝

Answer 1

我希望它可能對其他人有所幫助，就像在看到其他人的許多建議和回復之后一樣。 我剛剛想通了，有一種改變的方式可以執行原始查詢，就像在 SQL 服務器中一樣。

例如，您可以通過在 EF 中這樣使用來執行原始查詢

using (var command = _ctx.Database.GetDbConnection().CreateCommand())
       {
           command.CommandText = "select * from MARK where tid ='123'";
           _ctx.Database.OpenConnection();
           using (var reader = command.ExecuteReader())
                {

                    reader.Read();
                    var firstColumnObject = reader.GetValue(0); 
                }
             _ctx.Database.CloseConnection();
       
        }