Hibernate——将具有单个值的视图映射到只读字段
（Hibernate 3.6，Mysql 5）
我有一个名为“Program”的映射类（工作正常）。
我还有一个每天更新汇总统计数据的视图。
视图模式如下：
view ProgramSummary {
long program_id
long value
}
program_id 是唯一的，但没有 row-id。我想要的只是提取值，但我似乎无法找出正确的语义。
我尝试过使用 OneToOne（和 ManyToOne）关系映射一个单独的实体，但 id 之间会出现混淆。如果不将program_id标记为实体，hibernate将无法处理实际的映射。
有没有一种简单的方法可以做到这一点？它是一个由外部进程访问的只读字段，我没有任何更改架构的余地。
(Hibernate 3.6, Mysql 5)
I have a mapped class called 'Program' (that is working correctly).
I also have a view that is updated daily with aggregate statistics.
The view schema is like so:
view ProgramSummary {
long program_id
long value
}
program_id is unique, but there is no row-id. What I want is to just pull the value out, but I can't seem to figure out the right semantics.
I have tried mapping a separate entitiy with a OneToOne (and ManyToOne) relationship, but it gets confused between the ids. Without marking program_id as an entity, hibernate can't handle the actual mapping.
Is there a simple way to do this? It is a read-only field that is accessed by an external process and I don't have any leeway for changing the schema.
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您可以使用程序 hbm 文件中的公式来映射它。
假设您的字段名为 SummaryValue，此行将更新 Program 对象中的该字段。任何使用公式映射的字段都不可更新。
You can use a formula in your Program hbm file to map this.
Assuming your field is named SummaryValue this line will update that field in the Program object. Any field mapped with a formula is not updateable.
如果您映射第二个实体，您可能需要将列设置为
updatable=false和insertable=false，使其只读。但是，为什么不直接从 ProgramSummary 中选择值（可能使用纯 SQL）呢？
If you map a second entity, you might want to set the columns to
updatable=falseandinsertable=false, making them readonly.However, why don't you just select the value from ProgramSummary, probably with plain SQL?