我有以下两个表:
作业 AreaID,JobNo(复合键)
记录 LogID,AreaID,JobNo
我需要获取所有没有与之关联的日志的作业。在SQL中,我可以这样做:
SELECT Jobs.AreaID,
Jobs.JobNo
FROM Jobs
LEFT JOIN Logs
ON Jobs.AreaID = Logs.AreaID
AND Jobs.JobNo = Logs.JobNo
WHERE Logs.LogID is null
但我不知道如何用NHibernate来实现这个目标。任何人都可以提供任何指示吗?
以下是我的映射:
<class name="Job" table="Jobs">
<composite-key name="Id">
<key-property name="JobNo"/>
<key-many-to-one name="Area" class="Area" column="AreaID"/>
</composite-key>
</class>
<class name="Log" table="Logs">
<id name="Id" column="LogID">
<generator class="identity"/>
</id>
<property name="JobNo"/>
<many-to-one name="Area" class="Area" column="AreaID"/>
</class>
由于
更新
好的,我稍微修改了诺西拉的答案,现在正在做我想要的事情:
Log logs = null;
return session.QueryOver<Job>()
.Left.JoinAlias(x => x.Logs, () => logs)
.Where(x => logs.Id == null)
.List<Job>();
我还必须将此添加到我的作业映射中:
<bag name="Logs">
<key>
<column name="JobNo"></column>
<column name="DivisionID"></column>
</key>
<one-to-many class="Log"/>
</bag>
感谢您的帮助。 :)
答案 0 :(得分:6)
我不熟悉复合标识符,因为我不使用它们,所以我知道NHibernate将自动创建正确的左连接。尽管如此,下面的(未经测试的)查询应该可以帮助您入门。
Job jobAlias = null;
Log logAlias = null;
YourDto yourDto = null;
session.QueryOver<Job>()
// Here is where we set what columns we want to project (e.g. select)
.SelectList(x => x
.Select(x => x.AreaID).WithAlias(() => jobAlias.AreaID)
.Select(x => x.JobNo).WithAlias(() => jobAlias.JobNo)
)
.Left.JoinAlias(x => x.Logs, () => logAlias, x.JobNo == logAlias.JobNo)
.Where(() => logAlias.LogID == null)
// This is where NHibernate will transform what you have in your `SelectList()` to a list of objects
.TransformUsing(Transformers.AliasToBean<YourDto>())
.List<YourDto>();
public class YourDto
{
public int AreaID { get; set; }
public int JobNo { get; set; }
}
注意:您需要NHibernate 3.2才能设置连接条件。
答案 1 :(得分:4)
Job job = null;
var jobsWithoutLogs = session.QueryOver(() => job)
.WithSubquery.WhereNotExists(QueryOver.Of<Log>()
.Where(log => log.Job == job)
.Select(Projections.Id()))
.List()
更新:我看到你添加了映射。以上代码仅适用于以下映射
<class name="Log" table="Logs">
<id name="Id" column="LogID">
<generator class="identity"/>
</id>
<many-to-one name="Job" >
<column name="JobNo"/>
<column name="AreaID"/>
<many-to-one />
</class>