java - Hibernate native 查询显示异常

Question

我编写了 Hibernate native 查询，用于从表中获取总用户和月份。
但它显示:

exception:Operand should contain 1 column(s)
org.hibernate.exception.DataException: could not execute query

有人可以帮我解决这个问题吗:

  c.setProjection(Projections.projectionList()
     .add(Projections.sqlProjection("(select count(*), MONTH(Stored) from adbtbl_stat " 
     + "where Activity = 89 and YEAR(Stored) = 2015) as Count, month",
     new String[] { "Count", "month" }, new Type[] { LongType.INSTANCE, StringType.INSTANCE }))
     .add(Projections.groupProperty(month(stored))));

Answer 1

一个ProjectionList可以包含多个SQLProjection(s) ，但每个 SQLProjection 应该与一个且仅一个 SQL 列相关联。

您 SQLProjection 尝试选择两列。

尝试用简单的 native 查询替换您的 Criteria 查询:

Long activity = ...;
int year = ...;

Query q = entityManager.createNativeQuery(
    "select count(*) as Count, MONTH(Stored) as Month " +
    "from adbtbl_stat " +
    "where Activity = :activity and YEAR(Stored) = :year"
);
q.setParameter("activity", activity);
q.setParameter("year", year);
List<Object[]> result = (List<Object[]>) q.getResultList();