LINQ 联查多表数据并封装到ViewModel的实现-优快云博客

本文介绍了一个使用LINQ进行多表联查的方法，并将查询结果封装到ViewModel中。具体实现了从任务参与表、任务信息表、任务类型表及成员信息表中联查数据，按条件筛选后返回分页的任务列表。

LINQ 联查多表数据并封装到ViewModel的实现

public List<MyTask> GetPagedTaskList(int pageIndex, int pageSize, string stuNum, int taskTypeId)
{

            DbSet<T_TaskParticipation> taskParticipations = db.Set<T_TaskParticipation>();
            DbSet<T_TaskInformation> taskInformations = db.Set<T_TaskInformation>();
            DbSet<T_TaskType> taskTypes = db.Set<T_TaskType>();
            DbSet<T_MemberInformation> memberInformations = db.Set<T_MemberInformation>();

            List<MyTask> myTaskList = (from taskParticipation in taskParticipations
                        join taskInformation in taskInformations on taskParticipation.TaskId equals taskInformation.TaskId
                        join taskType in taskTypes on taskInformation.TaskTypeId equals taskType.TaskTypeId
                        join memberInformation in memberInformations on taskInformation.TaskSender equals memberInformation.StuNum
                        where taskParticipation.TaskReceiver == stuNum
                        && taskInformation.TaskTypeId == taskTypeId
                        select new MyTask()
                        {
                            TaskId=taskParticipation.TaskId,
                            TaskSender=taskInformation.TaskSender,
                            TaskName=taskInformation.TaskName,
                            TaskTypeId=taskInformation.TaskTypeId,
                            TaskContent=taskInformation.TaskContent,
                            TaskBegTime=taskInformation.TaskBegTime,
                            TaskEndTime=taskInformation.TaskEndTime,
                            TaskReceiver=taskParticipation.TaskReceiver,
                            TaskGrade=taskParticipation.TaskGrade,
                            IsRead=taskParticipation.IsRead,
                            IsComplete=taskParticipation.IsComplete,
                            TaskSenderName=memberInformation.StuName,
                            TaskTypeName=taskType.TaskTypeName
                        }).OrderBy(taskParticipation => taskParticipation.IsRead).ThenBy(taskParticipation => taskParticipation.TaskId).Skip((pageIndex - 1) * pageSize).Take(pageSize).ToList();