Question

我有很多表格，如：

User_cs
UserEducation_cs
体验

以下是数据库图表

我需要的是用户信息

来自User_cs的基本信息
他们的最后一次教育（即他们获得的最新学位）
它们当前正在工作（如果用户不工作），Experience_cs中的字段将为NULL。

我到目前为止能够做到以下但是我遇到了麻烦1）在lamda表达式中间我是如何做的（IsWorking == true）并且继续加入到下一个表。以下是我的表达

   List<Models.UserInfo> v = context.User_cs
            .Join(context.UserEducation_cs, u => u.UserName, ue => ue.UserName, (u, ue) => new UserEducation_cs
            {
                UserName = ue.UserName,
                EducationId = ue.EducationId,
                StartDate = ue.StartDate,
                EndDate = ue.EndDate
            }).
            Join(context.Education_cs, ue => ue.EducationId, e => e.EducationId, (ue, e) => new
            {
                UserName = ue.UserName,
                EducationId = ue.EducationId,
                StartDate = ue.StartDate,
                EndDate = ue.EndDate,
                Title = e.Title,
                Major = e.Major,
                MajorDetails = e.MajorDetails,
                Info = e.Info
            }).
            Join(context.Experiences, lst => lst.UserName, ex => ex.UserName, (lst, ex) => new Models.UserInfo
            {
                UserName = ex.UserName,
                EducationId = lst.EducationId,
                StartDate = lst.StartDate,
                EndDate = lst.EndDate,
                Title = lst.Title,
                Major = lst.Major,
                MajorDetails = lst.MajorDetails,
                Info = lst.Info,
                IsWorking = ex.IsWorking,
                StartDate_ex=ex.StartedDate,                    
            }).
            Where(iw => iw.IsWorking == true).ToList();

任何帮助将不胜感激

Answer 1

我不完全确定我是否完全理解你的问题。我认为您需要在将（内部）联接应用于它们之前过滤您的列表。要为每个Education_cs仅获取最新的User_cs条目，我想您可以使用分组。另外，我还没有完全测试过这段代码：

List<Models.UserInfo> v = context.User_cs
        .Join(context.UserEducation_cs, u => u.UserName, ue => ue.UserName, (u, ue) => new UserEducation_cs
        {
            UserName = ue.UserName,
            EducationId = ue.EducationId,
            StartDate = ue.StartDate,
            EndDate = ue.EndDate
        }).
        Join(context.Education_cs.GroupBy(q => q.UserName).Select(q => q.OrderByDescending(w => w.StartDate).First()), 
             ue => ue.EducationId, e => e.EducationId, (ue, e) => new
        {
            UserName = ue.UserName,
            EducationId = ue.EducationId,
            StartDate = ue.StartDate,
            EndDate = ue.EndDate,
            Title = e.Title,
            Major = e.Major,
            MajorDetails = e.MajorDetails,
            Info = e.Info
        }).
        Join(context.Experiences.Where(ex => ex.IsWorking), lst => lst.UserName, ex => ex.UserName, (lst, ex) => new Models.UserInfo
        {
            UserName = ex.UserName,
            EducationId = lst.EducationId,
            StartDate = lst.StartDate,
            EndDate = lst.EndDate,
            Title = lst.Title,
            Major = lst.Major,
            MajorDetails = lst.MajorDetails,
            Info = lst.Info,
            IsWorking = ex.IsWorking,
            StartDate_ex=ex.StartedDate,                    
        }).ToList();

具有多个连接的Linq表达式与每个连接中的条件

1 个答案: