Mysql 将复杂SQL查询转换为LINQ

我对SQL有丰富的经验，但对LINQ还是相当陌生的，我正在努力将下面的MySQL查询转换为LINQ。 是否有人可以帮助将以下内容转换为LINQ，以便在具有实体框架的ASP.net MVC项目中使用

SELECT
    S.Submission_ID,
    P.Photo_ID,
    C2.Contract_Name,
    J.Job_Number,
    D.Device_Name,
    A.`Display_Name`,
    S.Submission_Status,
    S.Submission_JobRef,
    S.Created,
    TRUE
FROM
    Submission S
        LEFT JOIN Job J ON S.`Job_ID` = J.`Job_ID`
        LEFT JOIN Contract C2 ON J.`Contract_ID` = C2.`Contract_ID`
        INNER JOIN Submission_Status SS ON S.`Submission_Status` = SS.`ID`
        INNER JOIN Device D ON S.`Device_ID` = D.`Device_ID`
        INNER JOIN ACTION A ON S.`Action_ID` = A.`Action_ID`
        INNER JOIN (
            SELECT
                MIN(P.Photo_ID) AS Photo_ID,
                P.Submission_ID
            FROM
                Photo P
            GROUP BY
                P.`Submission_ID`) P ON S.`Submission_ID` = P.Submission_ID
WHERE
    S.`Submission_Status` <> 3 AND
    (LOCATE(@Criteria, C2.`Contract_Name`) > 0 OR
    LOCATE(@Criteria, J.`Job_Number`) > 0 OR
    LOCATE(@Criteria, D.`Device_Name`) > 0 OR
    LOCATE(@Criteria, A.`Display_Name`) > 0 OR
    LOCATE(@Criteria, SS.`Value`) > 0 OR
    LOCATE(@Criteria, S.`Submission_JobRef`) > 0)
ORDER BY
    S.`Submission_ID` DESC

如有任何上述帮助或指导，将不胜感激

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编辑 为了提供帮助，下面是模型中的类，这些类定义了上述查询中使用的实体。（我省略了一些与问题无关的领域）

---

这是一段相当复杂的SQL语句，包含一个子选择和左连接与内连接的混合。 一些快速建议：

将其分解为一系列linq语句，从核心对象开始，在后续步骤中添加相关部分。如果您将结果保留为IQueryable，编译器将为您将所有结果放在一起，并将其作为一个查询发送到db（即，直到最后一步才发送ToList（）

就我个人而言，我使用两个from和一个where扩展方法进行连接，而不是使用连接操作符。首先，我让你更容易知道你得到的是左连接还是内连接

例如：

FROM Submission S LEFT JOIN Job J ON S.`Job_ID` = J.`Job_ID`

我会这样做（对不起，我是c#所以VB的语法可能不太正确）

因此，联接条件在作业的.Where（）中，并且.DefaultIfEmpty（）告诉它左联接（本质上，如果联接失败，作业将是默认的）

进一步编辑：

经过实验，我得到了返回结果的代码（正确的结果是另一个问题）。再次为c#语法感到抱歉

显然，您可以在测试中改变标准常量以应用于不同的项目，我选择匹配合同-我假设只有一个表匹配

此查询生成以下SQL，看起来有点古怪，但在功能上与原始SQL非常相似

SELECT 
    [Filter1].[SubmissionId] AS [SubmissionId], 
    [GroupBy1].[A1] AS [C1], 
    [Filter1].[ContractName] AS [ContractName], 
    [Filter1].[JobNumber] AS [JobNumber], 
    [Filter1].[DeviceName] AS [DeviceName], 
    [Filter1].[DisplayName] AS [DisplayName], 
    [Filter1].[SubmissionStatus] AS [SubmissionStatus], 
    [Filter1].[SubmissionJobRef] AS [SubmissionJobRef], 
    [Filter1].[Created] AS [Created], 
    cast(1 as bit) AS [C2]
FROM   
(
    SELECT 
        [Extent1].[SubmissionId] AS [SubmissionId], 
        [Extent1].[SubmissionStatus] AS [SubmissionStatus], 
        [Extent1].[SubmissionJobRef] AS [SubmissionJobRef], 
        [Extent1].[Created] AS [Created], 
        [Extent2].[JobNumber] AS [JobNumber], 
        [Extent3].[ContractName] AS [ContractName], 
        [Extent4].[Value] AS [Value], 
        [Extent5].[DeviceName] AS [DeviceName], 
        [Extent6].[DisplayName] AS [DisplayName]
    FROM      
        [dbo].[Submissions] AS [Extent1]
        LEFT OUTER JOIN [dbo].[Jobs] AS [Extent2] ON [Extent2].[JobId] = [Extent1].[JobId]
        LEFT OUTER JOIN [dbo].[Contracts] AS [Extent3] ON [Extent3].[ContractId] = [Extent2].[ContractId]
        INNER JOIN [dbo].[SubmissionStatus] AS [Extent4] ON [Extent4].[Id] = [Extent1].[SubmissionStatus]
        INNER JOIN [dbo].[Devices] AS [Extent5] ON [Extent5].[DeviceId] = [Extent1].[DeviceId]
        INNER JOIN [dbo].[Actions] AS [Extent6] ON [Extent6].[ActionId] = [Extent1].[ActionId]
    WHERE 
        3 <> [Extent1].[SubmissionStatus] 
) AS [Filter1]

INNER JOIN  (
    SELECT 
        [Extent7].[SubmissionId] AS [K1], 
        MIN([Extent7].[PhotoId]) AS [A1]
    FROM 
        [dbo].[Photos] AS [Extent7]
    GROUP BY 
        [Extent7].[SubmissionId] ) AS [GroupBy1] 
    ON [GroupBy1].[K1] = [Filter1].[SubmissionId]
WHERE 
(
    [Filter1].[ContractName] LIKE @p__linq__0 ESCAPE N'~') OR 
    ([Filter1].[JobNumber] LIKE @p__linq__1 ESCAPE N'~') OR 
    ([Filter1].[DeviceName] LIKE @p__linq__2 ESCAPE N'~') OR 
    ([Filter1].[DisplayName] LIKE @p__linq__3 ESCAPE N'~') OR 
    ([Filter1].[Value] LIKE @p__linq__4 ESCAPE N'~') OR 
    ([Filter1].[SubmissionJobRef] LIKE @p__linq__5 ESCAPE N'~')
)   

选择
[Filter1]。[SubmissionId]作为[SubmissionId]，
[GroupBy1][A1]作为[C1]，
[Filter1]。[ContractName]作为[ContractName]，
[Filter1]。[JobNumber]作为[JobNumber]，
[Filter1]。[DeviceName]作为[DeviceName]，
[Filter1]。[DisplayName]作为[DisplayName]，
[Filter1]。[SubmissionStatus]作为[SubmissionStatus]，
[Filter1][SubmissionJobRef]作为[SubmissionJobRef]，
[Filter1]。[Created]作为[Created]，
按[C2]铸造（1为位）
从…起
(
挑选
[Extent1]。[SubmissionId]作为[SubmissionId]，
[Extent1]。[SubmissionStatus]作为[SubmissionStatus]，
[Extent1][SubmissionJobRef]作为[SubmissionJobRef]，
[Extent1].[Created]作为[Created]，
[Extent2]。[JobNumber]作为[JobNumber]，
[Extent3]。[ContractName]作为[ContractName]，
[Extent4]。[Value]作为[Value]，
[Extent5]。[DeviceName]作为[DeviceName]，
[Extent6]。[DisplayName]作为[DisplayName]
从…起
[dbo].[Submissions]作为[Extent1]
[Extent2].[JobId]=[Extent1].[JobId]上作为[Extent2]的左外部联接[dbo].[Jobs]
左外联接[dbo].[Contracts]作为[Extent3]在[Extent3].[contracted]=[Extent2].[contracted]上的[Extent3]
在[Extent4].[Id]=[Extent1].[SubmissionStatus]上将[dbo].[SubmissionStatus]作为[Extent4]进行内部联接
将[dbo].[Devices]作为[Extent5].[DeviceId]=[Extent1].[DeviceId]上的[Extent5]进行内部联接
将[dbo].[Actions]作为[Extent6].[ActionId]=[Extent1].[ActionId]上的[Extent6]进行内部联接
哪里
3[扩展1][提交状态]
)AS[Filter1]
内连接(
挑选
[Extent7]。[SubmissionId]作为[K1]，
最小值（[Extent7][PhotoId]）为[A1]
从…起
[dbo].[Photos]作为[Extent7]
分组
[Extent7][SubmissionId]）作为[GroupBy1]
在[GroupBy1].[K1]=[Filter1].[SubmissionId]上
哪里
(
[Filter1]。[ContractName]如@p__linq____0 ESCAPE N'~'）或
（[Filter1].[JobNumber]像@p__linq____1 ESCAPE N'~'）或
（[Filter1].[DeviceName]如@p_ulinq_u2 ESCAPE N'~）或
（[Filter1].[DisplayName]如@p_ulinq_u3 ESCAPE N'~'）或
（[Filter1].[Value]像@p_ulinq_u4 ESCAPE N'~'）或
（[Filter1].[SubmissionJobRef]类似于@p_ulinq_u5 ESCAPE N'~）
)   

用一句话回应Dave Johnson的评论-可伸缩性

最近，我试图提高应用程序的性能，我的第一个想法是在John Henry的示例中添加一些复杂性类似的SQL—多连接和过滤器。毕竟，它在我的开发机器上的表现就像火箭一样

这位架构师断然禁止在数据库服务器上使用复杂的SQL，因为有几个拥有100多个用户的大型应用程序与之挂钩。尽管我非常喜欢构建快速的SQL，但我不得不同意。将逻辑转移到使用它的机器上是一种很好的架构

因此，对于我们这些精通声明式SQL的人来说，学习linq翻译技巧非常重要

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当然，我前面给出的解决方案无法实现这一点，因为相同的SQL被发送到服务器。但是拥有一个linq等价物是一个可以进一步优化的开始。

在大量搜索和阅读各种文章之后，我放弃了用linq查询语法编写此查询，转而使用方法语法

非常感谢Ackroydd在将复杂SQL转换为LINQ方面提供的建议和支持。当您知道您可以在几分钟内用SQL完成一些事情，但需要使用LINQ实现可伸缩性并与现有代码保持一致时，您可能会感到相当沮丧

以下是我的结论，因为我相信它对其他人会有用：

Dim query As IQueryable(Of Submission)

' Initialise the new query
query = db.Submissions.Include(Function(s) s.Action) _
                              .Include(Function(s) s.Photos) _
                              .Include(Function(s) s.Device) _
                              .Include(Function(s) s.Job) _
                              .Include(Function(s) s.Submission_Status1) _
                              .Include(Function(s) s.Job.Contract) _
                              .Include(Function(s) s.Comments) _
                              .AsNoTracking

' Apply initial filters
query = query.Where(Function(S) Not S.Submission_Status1.ID.Equals(3))

' Apply search criteria if passed
If Not String.IsNullOrEmpty(param.sSearch) Then
    query = query.Where(Function(S) S.Job.Contract.Contract_Name.Contains(param.sSearch) OrElse
                                            S.Job.Job_Number.Contains(param.sSearch) OrElse
                                            S.Device.Device_Name.Contains(param.sSearch) OrElse
                                            S.Action.Display_Name.Contains(param.sSearch) OrElse
                                            S.Submission_Status1.Value.Contains(param.sSearch) OrElse
                                            S.Submission_JobRef.Contains(param.sSearch))
End If

' Order the results
query = query.OrderByDescending(Function(S) S.Submission_ID)

' Paginate the results
query = query.Skip(param.iDisplayStart).Take(param.iDisplayLength)

' Return only the required columns
Dim resultData = query.AsEnumerable.Select(Function(S) New AjaxSubmissionOverview With { _
                                                           .Submission_ID = S.Submission_ID,
                                                           .Photo_ID = S.Photos.First.Photo_ID,
                                                           .Contract_Name = If(IsNothing(S.Job), "", S.Job.Contract.Contract_Name),
                                                           .Job_Number = If(IsNothing(S.Job), "", S.Job.Job_Number),
                                                           .Device_Name = S.Device.Device_Name,
                                                           .Action_Name = S.Action.Display_Name,
                                                           .Submission_Status = S.Submission_Status,
                                                           .Submission_JobRef = S.Submission_JobRef,
                                                           .Latest_Comment = If(S.Comments.Count = 0, "", HtmlHelpers.Truncate(S.Comments.Last.Comment1, 100)),
                                                           .Created = S.Created,
                                                           .CanEdit = bolCanEdit})

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首先，你应该试着做点什么…导航属性非常重要，所以请显示实体模型的相关部分。为什么你会接受这样一个有效的查询并希望将其转换为LINQ？我会投票支持你的问题，但级别不够高。我认为，这是一个很好的问题。至少，我花了一段时间才熟练地将SQL翻译成等效的linq，并确定结果

Dim results = from s in db.Submissions
              from j in db.Jobs.Where(j=> j.Job_Id == s.Job_Id).DefaultIfEmpty()

    [TestMethod]
    public void Query()
    {
        const string conStr = "Data Source=(local);Initial Catalog=ComplexSqlToLinq; Integrated Security=True";
        var db = new MyDbContext(conStr);

        const string criteria = "Contract1";

        var minPhotos = from p in db.Photos
                        group p by p.SubmissionId
                        into g
                        select new {SubmissionId = g.Key, PhotoId = g.Min(p=>p.PhotoId)};

        var query = from s in db.Submissions
                    from j in db.Jobs.Where(j => j.JobId == s.JobId).DefaultIfEmpty()
                    from c in db.Contracts.Where(c => c.ContractId == j.ContractId).DefaultIfEmpty()
                    from ss in db.SubmissionStatuses.Where(ss => ss.Id == s.SubmissionStatus)
                    from d in db.Devices.Where(d => d.DeviceId == s.DeviceId)
                    from a in db.Actions.Where(a => a.ActionId == s.ActionId)
                    from p in minPhotos.Where(p => p.SubmissionId == s.SubmissionId)

                    where s.SubmissionStatus != 3 &&
                       ( c.ContractName.Contains(criteria) ||
                         j.JobNumber.Contains(criteria) ||
                         d.DeviceName.Contains(criteria) ||
                         a.DisplayName.Contains(criteria) ||
                         ss.Value.Contains(criteria) ||
                         s.SubmissionJobRef.Contains(criteria))

                    select new
                               {
                                   s.SubmissionId,
                                   p.PhotoId,
                                   c.ContractName,
                                   j.JobNumber,
                                   d.DeviceName,
                                   a.DisplayName,
                                   s.SubmissionStatus,
                                   s.SubmissionJobRef,
                                   s.Created,
                                   SomeBool = true
                               };

        var result = query.ToList();
        Assert.IsTrue(result.Any());
    }

SELECT 
    [Filter1].[SubmissionId] AS [SubmissionId], 
    [GroupBy1].[A1] AS [C1], 
    [Filter1].[ContractName] AS [ContractName], 
    [Filter1].[JobNumber] AS [JobNumber], 
    [Filter1].[DeviceName] AS [DeviceName], 
    [Filter1].[DisplayName] AS [DisplayName], 
    [Filter1].[SubmissionStatus] AS [SubmissionStatus], 
    [Filter1].[SubmissionJobRef] AS [SubmissionJobRef], 
    [Filter1].[Created] AS [Created], 
    cast(1 as bit) AS [C2]
FROM   
(
    SELECT 
        [Extent1].[SubmissionId] AS [SubmissionId], 
        [Extent1].[SubmissionStatus] AS [SubmissionStatus], 
        [Extent1].[SubmissionJobRef] AS [SubmissionJobRef], 
        [Extent1].[Created] AS [Created], 
        [Extent2].[JobNumber] AS [JobNumber], 
        [Extent3].[ContractName] AS [ContractName], 
        [Extent4].[Value] AS [Value], 
        [Extent5].[DeviceName] AS [DeviceName], 
        [Extent6].[DisplayName] AS [DisplayName]
    FROM      
        [dbo].[Submissions] AS [Extent1]
        LEFT OUTER JOIN [dbo].[Jobs] AS [Extent2] ON [Extent2].[JobId] = [Extent1].[JobId]
        LEFT OUTER JOIN [dbo].[Contracts] AS [Extent3] ON [Extent3].[ContractId] = [Extent2].[ContractId]
        INNER JOIN [dbo].[SubmissionStatus] AS [Extent4] ON [Extent4].[Id] = [Extent1].[SubmissionStatus]
        INNER JOIN [dbo].[Devices] AS [Extent5] ON [Extent5].[DeviceId] = [Extent1].[DeviceId]
        INNER JOIN [dbo].[Actions] AS [Extent6] ON [Extent6].[ActionId] = [Extent1].[ActionId]
    WHERE 
        3 <> [Extent1].[SubmissionStatus] 
) AS [Filter1]

INNER JOIN  (
    SELECT 
        [Extent7].[SubmissionId] AS [K1], 
        MIN([Extent7].[PhotoId]) AS [A1]
    FROM 
        [dbo].[Photos] AS [Extent7]
    GROUP BY 
        [Extent7].[SubmissionId] ) AS [GroupBy1] 
    ON [GroupBy1].[K1] = [Filter1].[SubmissionId]
WHERE 
(
    [Filter1].[ContractName] LIKE @p__linq__0 ESCAPE N'~') OR 
    ([Filter1].[JobNumber] LIKE @p__linq__1 ESCAPE N'~') OR 
    ([Filter1].[DeviceName] LIKE @p__linq__2 ESCAPE N'~') OR 
    ([Filter1].[DisplayName] LIKE @p__linq__3 ESCAPE N'~') OR 
    ([Filter1].[Value] LIKE @p__linq__4 ESCAPE N'~') OR 
    ([Filter1].[SubmissionJobRef] LIKE @p__linq__5 ESCAPE N'~')
)   

Dim query As IQueryable(Of Submission)

' Initialise the new query
query = db.Submissions.Include(Function(s) s.Action) _
                              .Include(Function(s) s.Photos) _
                              .Include(Function(s) s.Device) _
                              .Include(Function(s) s.Job) _
                              .Include(Function(s) s.Submission_Status1) _
                              .Include(Function(s) s.Job.Contract) _
                              .Include(Function(s) s.Comments) _
                              .AsNoTracking

' Apply initial filters
query = query.Where(Function(S) Not S.Submission_Status1.ID.Equals(3))

' Apply search criteria if passed
If Not String.IsNullOrEmpty(param.sSearch) Then
    query = query.Where(Function(S) S.Job.Contract.Contract_Name.Contains(param.sSearch) OrElse
                                            S.Job.Job_Number.Contains(param.sSearch) OrElse
                                            S.Device.Device_Name.Contains(param.sSearch) OrElse
                                            S.Action.Display_Name.Contains(param.sSearch) OrElse
                                            S.Submission_Status1.Value.Contains(param.sSearch) OrElse
                                            S.Submission_JobRef.Contains(param.sSearch))
End If

' Order the results
query = query.OrderByDescending(Function(S) S.Submission_ID)

' Paginate the results
query = query.Skip(param.iDisplayStart).Take(param.iDisplayLength)

' Return only the required columns
Dim resultData = query.AsEnumerable.Select(Function(S) New AjaxSubmissionOverview With { _
                                                           .Submission_ID = S.Submission_ID,
                                                           .Photo_ID = S.Photos.First.Photo_ID,
                                                           .Contract_Name = If(IsNothing(S.Job), "", S.Job.Contract.Contract_Name),
                                                           .Job_Number = If(IsNothing(S.Job), "", S.Job.Job_Number),
                                                           .Device_Name = S.Device.Device_Name,
                                                           .Action_Name = S.Action.Display_Name,
                                                           .Submission_Status = S.Submission_Status,
                                                           .Submission_JobRef = S.Submission_JobRef,
                                                           .Latest_Comment = If(S.Comments.Count = 0, "", HtmlHelpers.Truncate(S.Comments.Last.Comment1, 100)),
                                                           .Created = S.Created,
                                                           .CanEdit = bolCanEdit})