左连接linq到sql

本文关键字：sql linq 连接 | 更新日期: 2023-09-27 18:10:56

我有这样的查询:

public IEnumerable<TimesheetModel> GetTicketsInProgressByUserId(int id)
{
    var query = (from workLogList in DataContext.tblWorkLogs
                 join tickets in DataContext.tblTickets on workLogList.TicketId equals tickets.TicketId
                 join project in DataContext.tblProjects on tickets.ProjectId equals project.ProjectId
                 join states  in DataContext.tblWorkflowStates on tickets.Status equals states.StateId
                 where workLogList.AccountId == id
                 group workLogList by workLogList.WorkDate into data
                 select new TimesheetModel
                 {
                     TaskDate = data.Key,
                     TimesheetList = data.Select(x => new TimesheetListModel()
                     {
                         ProjectId = x.tblTicket.tblProject.ProjectId,
                         ProjectName = x.tblTicket.tblProject.Name,
                         TaskDate = x.WorkDate,
                         TimeWorked = x.TimeWorked,
                         Note = x.Note,
                         Task = TaskString(x.tblTicket.TicketId, x.tblTicket.Title, x.TaskTitle)
                     }
                     ).ToList()
                 });
    return query.ToList();
}

在这一行中，我需要使用左连接，因为我还需要使用worklogList.TicketId == null

获取数据
join tickets in DataContext.tblTickets on workLogList.TicketId equals tickets.TicketId

如何在这种情况下使用左连接?

左连接linq到sql

如果您只是在模型中建立关联，那么请记住将基数设置为0。1 - *.

那么你应该能够使用点语法，而不是在linq语句中连接。

补充道:

下面是我希望你在做了这些关联(当然是未经测试的)之后结束的例子:

(from workLogList in DataContext.tblWorkLogs
             //join tickets in DataContext.tblTickets on workLogList.TicketId equals tickets.TicketId
             //join project in DataContext.tblProjects on tickets.ProjectId equals project.ProjectId
             //join states  in DataContext.tblWorkflowStates on tickets.Status equals states.StateId
             where workLogList.AccountId == id
             group workLogList by workLogList.WorkDate into data
             select new TimesheetModel
             {
                 TaskDate = data.Key,
                 TimesheetList = data.Select(x => new TimesheetListModel()
                 {
                     ProjectId = x.tblTicket.tblProject.ProjectId,
                     ProjectName = x.tblTicket.tblProject.Name,
                     TaskDate = x.WorkDate,
                     TimeWorked = x.TimeWorked,
                     Note = x.Note,
                     Task = TaskString(x.tblTicket.TicketId, x.tblTicket.Title, x.TaskTitle)
                 }
                 ).ToList()
             });
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