Hibernate中使用Criteria接口的Projections类处理聚合结果

Projections类主要用于帮助Criteria接口完成数据的分组查询和统计功能




List cats=session.createCriteria(Cat.class)


.setProjection(Projections.projectionList()


.add(Projections.rowCount())


.add(Projections.avg("weight"))


.add(Projections.max("weight"))


.add(Projections.min("weight"))


.add(Projections.groupProperty("color"))


).addOrder(Order.asc("color")).list();









以上代码相当于select color,count(*),avg(weight),max(weight),min(weight),min(weight) from cat group by color
order by color asc;