Question

我正在尝试使用此sql查询并将其转换为nhibernate HQL查询。我正在使用nhibernate 3和Fluent Nhibernate 1.2

SELECT     dbo.Tasks.CourseId, dbo.CoursePermissions.BackgroundColor, dbo.Tasks.DueDate, dbo.Tasks.TaskName, dbo.Tasks.TaskId
FROM         dbo.Courses INNER JOIN
                      dbo.Tasks ON dbo.Courses.CourseId = dbo.Tasks.CourseId INNER JOIN
                      dbo.CoursePermissions ON dbo.Courses.CourseId = dbo.CoursePermissions.CourseId
WHERE     (dbo.Tasks.CourseId = 1)

我本来想使用linq，但我不认为nhibernate支持linq加入，所以我想我坚持使用HQL（除非有人知道更好的方法）。

我想我可以使用QueryOver或其他方式nhibernate进行查询，所以无论什么效果最好。我仍然不明白所有方式之间的区别，好像我可以在linq中做所有事情。

但是我不清楚如何编写查询。

由于

修改

我现在有了这个（改了一下）

课程cAlias = null; 任务tAlias = null; CoursePermission cpAlias = null;

    var result = session.QueryOver<Task>(() => tAlias)
        .JoinAlias(() => tAlias.Course, () => cAlias)
        .JoinAlias(() => cAlias.CoursePermissions, () => cpAlias)
        .Where(Restrictions.In(Projections.Property(() => cAlias.Id), courseIds))
        .And(x => x.DueDate >= startDate)
        .And(x => x.DueDate <= endDate)
        .Select( Projections.Property(() => cAlias.Id),
                Projections.Property(() => cpAlias.BackgroundColor),
                Projections.Property(() => tAlias.DueDate),
                Projections.Property(() => tAlias.TaskName),
                Projections.Property(() => tAlias.TaskId))
        .List<object[]>();

我知道要将它映射到

公共类TaskAppointments { public int Id {get;组; } public string BackgroundColor {get;组; } public DateTime DueDate {get;组; } public int TaskId {get;组; } public string TaskName {get;组; }

}

我该怎么做如果这是一个linq方法我会做

.Select(new TaskAppointments { TaskId = Projections.Property(() => tAlias.TaskId)})

但它表示无法将其转换为int。

EDIT2

这就是我想出来的

课程cAlias = null; 任务tAlias = null; CoursePermission cpAlias = null; TaskAppointments taskAppointments = null;

    List<TaskAppointments> result = session.QueryOver<Task>(() => tAlias)
        .JoinAlias(() => tAlias.Course, () => cAlias)
        .JoinAlias(() => cAlias.CoursePermissions, () => cpAlias)
        .Where(Restrictions.In(Projections.Property(() => cAlias.Id), courseIds))
        .And(x => x.DueDate >= startDate)
        .And(x => x.DueDate <= endDate)
        .SelectList(list => 

                            list.SelectGroup(x => x.TaskId).WithAlias(() => taskAppointments.TaskId)
                            .SelectGroup(() => cpAlias.BackgroundColor).WithAlias(() => taskAppointments.BackgroundColor)
                            .SelectGroup(x => x.DueDate).WithAlias(() => taskAppointments.DueDate)
                            .SelectGroup(x => x.TaskName).WithAlias(() => taskAppointments.TaskName)
                    )
        .TransformUsing(Transformers.AliasToBean<TaskAppointments>())
        .List<TaskAppointments>().ToList();

Answer 1

如果没有映射，我认为您有以下关系：Courses - ＆gt; Tasks（1：n）和Courses - ＆gt; CoursePermissions（1：n）我还假设你不需要完整的对象而只需要某些属性，因此我使用了投影。

QueryOver版本：

// the aliases are required here, so that we can reference the entities properly
Courses cAlias = null;
Tasks tAlias = null;
CoursePermissions cpAlias = null;

var result = session.QueryOver<Courses>(() => cAlias)
    .JoinAlias(() => cAlias.Tasks, () => tAlias)
    .JoinAlias(() => cAlias.CoursePermissions, () => cpAlias)
    .Where(() => cAlias.CourseId == 1)
    .Select(Projections.Property(() => cAlias.CourseId),
            Projections.Property(()  => cpAlias.BackgroundColor),
            Projections.Property(()  => tAlias.DueDate),
            Projections.Property(()  => tAlias.TaskName),
            Projections.Property(()  => tAlias.TaskId))
    .List<object[]>();

修改开始

如果您需要执行WHERE IN子句，可以执行以下操作：

List<int> courseIdList = new List<int>() { 1, 2 };

var result = session.QueryOver<Courses>(() => cAlias)
    .JoinAlias(() => cAlias.Tasks, () => tAlias)
    .JoinAlias(() => cAlias.CoursePermissions, () => cpAlias)
    .Where(Restrictions.In(Projections.Property(() => cAlias.CourseId), courseIdList))
    .Select(...)
    .List<object[]>();

修改结束

编辑2开始

如果您想将其转换为DTO：

// AliasToBeanResultTransformer is in namespace NHibernate.Transform
// we have to use .As("...") for the transformer to find the correct property-names
var result = ...
    .Select(Projections.Property(() => cAlias.CourseId).As("CourseId"),
            Projections.Property(()  => cpAlias.BackgroundColor).As("BackgroundColor"),
            Projections.Property(()  => tAlias.DueDate).As("DueDate"),
            Projections.Property(()  => tAlias.TaskName).As("TaskName"),
            Projections.Property(()  => tAlias.TaskId).As("TaskId"))
    .TransformUsing(new AliasToBeanResultTransformer(typeof(TaskAppointments)))
    .List<TaskAppointments>();

编辑2结束

HQL版本：

string hql = "select c.CourseId, cp.BackgroundColor, t.DueDate, t.TaskName, t.TaskId" 
   + " from Courses as c inner join c.Tasks as t inner join c.CoursePermissions as cp" 
   + " where c.CourseId = 1";

var result2 = session.CreateQuery(hql)
    .List<object[]>();

请注意，这将产生笛卡尔积，因此对于每个课程，您将获得Tasks.Count + CoursePermissions.Count行。

如何获取此sql查询并将其转换为nhibernate查询

1 个答案: