按月分组,在Hibernate中使用标准

Question

我正在尝试使用Criteria和ProjectionList获取报告,而我通过hibernate使用它是非常新的.所以我有这个模型:

private Long _userId;

 private Category _category;

 private Long _companyId;

 private Double _amount;

 private Date _date;

我用这个构建查询:

  public List sumPaymentsByUserCategoryPeriod(Category category, Long userId,Integer period){
  GregorianCalendar from = new GregorianCalendar();
  from.add(Calendar.MONTH, -period);
  List<CategoryAmount> resultDTO= new ArrayList<CategoryAmount>();

  Criteria criteria = getSession().createCriteria(Payment.class);
  criteria.add(Restrictions.eq("_category", category));
  criteria.add(Restrictions.eq("_userId",userId));
  criteria.add(Restrictions.between("_date", from.getTime(), new Date()));

  ProjectionList projectionList = Projections.projectionList();
  projectionList.add(Projections.sum("_amount"));
  projectionList.add(Projections.groupProperty("_date"));
  criteria.setProjection(projectionList);
  return  criteria.list();

 }

基本上这种方法会收到一个Category和一个userId来过滤付款记录和一个期间,这个期间将指示从现在到我想要总和多少个月.如何按月分组总和结果？

任何帮助或提示,我会很感激!

Answer 1

我找到了答案,而且非常简单.我更改了ProjectionList标准中的"groupProperty":

projectionList.add(Projections.sqlGroupProjection(
    "month({alias}.DATE) as month, year({alias}.DATE) as year", 
    "month({alias}.DATE), year({alias}.DATE)", 
    new String[]{"month","year"}, 
    new Type[] {Hibernate.DOUBLE}));

好的.我将解释sqlGroupProjection.第一个参数是"select"之后的查询部分,例如:

Select [firstPartOfSqlGroupProjection] * boo;

"{alias}"是休眠在查询中用于引用表的别名.

sqlGroupProjection函数的第二个参数是按条件分组,第三个参数是您将从组中获取的列名,最后是您将使用的数据类型.