Java Hibernate Projections.sqlGroupProjection别名_Java_Mysql_Hibernate_Projection

Java Hibernate Projections.sqlGroupProjection别名

java mysql hibernate

Java Hibernate Projections.sqlGroupProjection别名,java,mysql,hibernate,projection,Java,Mysql,Hibernate,Projection,我有一个标准像这样使用Hibernate public class Student { private Integer id,discriminatorColumn,discriminatorValue; //other stuff omitted for brevity } select sum(discriminatorValue) as rowCount from student group by discriminator_column having rowCount

我有一个

标准

像这样使用Hibernate

public class Student
{
    private Integer id,discriminatorColumn,discriminatorValue;
    //other stuff omitted for brevity
}

select sum(discriminatorValue) as rowCount
from student
group by discriminator_column
having rowCount>0

此实体有一个

discriminatorColumn

，其值从1到10（从不

NULL

），每个

discriminatorColumn

都有一个

discriminatorValue

，其值从

1到100（从不NULL
）
示例：（学生数据）
等等
我正试图通过DiscriminatorColumn
获得DiscriminatorValue
分组的SUM

我的意思是，在上一个例子中，如果我按DiscriminatorColumn=1
过滤，我将收到SUM=16

final Criteria criteria = session.createCriteria(Student.class)
.setProjection(Projections.sqlGroupProjection(
    "sum({alias}.discriminatorValue) as rowCount",
    "hibernateAlias.discriminatorColumn having rowCount>0",
    new String[]{"rowCount"},
    Helper.HIBERNATE_INTEGER_INSTANCE
 ));

这就创建了rightSQL
我看到类似这样的东西
public class Student
{
    private Integer id,discriminatorColumn,discriminatorValue;
    //other stuff omitted for brevity
} 

select sum(discriminatorValue) as rowCount
from student
group by discriminator_column
having rowCount>0

问题是当我将resultSetTransformer
设置为Student.class时，我无法找到Hibernate在discriminatorValue
Java字段中填充discriminatorValue
列result的sum
的方式
为此，我认为应该使用以下参数newstring[]{“rowCount”}

但是我试过了
new String[]{"discriminatorValue"}
new String[]{"this.discriminatorValue"}
new String[]{"{alias}.discriminatorValue"}
new String[]{"{studentAlias}.discriminatorValue"} using alias in Criteria
new String[]{"rowCount as discriminatorValue"} 
new String[]{"rowCount as this_.discriminatorValue"}
and So On..

但似乎不可能我做错了什么？不可能吗<代码>将值求和设置为从数据库中检索规则时的简单属性

我已经写了我自己的变压器，但它有点烦人。

我自己找到了答案，我将在这里发布，以便能够帮助别人

Projections.sqlGroupProjection("sum({alias}.discriminatorValue) as rowCount","hibernateAlias.discriminatorColumn having rowCount>0",new String[]{"rowCount"},Helper.HIBERNATE_INTEGER_INSTANCE)

似乎

新字符串[]{“rowCount”}

中的

rowCount

别名仅用于mysql语法，或者仅被

标准引擎忽略

是否需要使用别名来填充EntityClass的属性改为使用

外部别名

例如：

yourProjections.add(Projections.alias(Projections.sqlGroupProjection("sum({alias}.discriminatorValue) as rowCount","hibernateAlias.discriminatorColumn having rowCount>0",new String[]{"rowCount"},Helper.HIBERNATE_INTEGER_INSTANCE),"discriminatorValue"));

只需将您的

sqlGroupProjections

包装在

投影中即可。别名

设置为与

Java类中的属性相匹配的别名

，Hibernate将使用求和结果填充，而非

不再需要自定义转换器

我希望能帮助别人

Projections.sqlGroupProjection("sum({alias}.discriminatorValue) as rowCount","hibernateAlias.discriminatorColumn having rowCount>0",new String[]{"rowCount"},Helper.HIBERNATE_INTEGER_INSTANCE)