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我有兩個表:研究和用戶研究,研究有userResearches列表使用@OneToMany映射到userResearch。我試圖執行一個簡單的HQL查詢爲什麼這個簡單的hql查詢不起作用?未分類SQLException
from Research r inner join r.userResearches ur where ur.user=:user
,並得到此異常:
Hibernate operation: could not execute query; uncategorized SQLException for SQL [select...]; SQL state [24000]; error code [0]; Operation requires a scrollable ResultSet, but this ResultSet is FORWARD_ONLY.; nested exception is org.postgresql.util.PSQLException: Operation requires a scrollable ResultSet, but this ResultSet is FORWARD_ONLY.
什麼能是什麼原因? 實體映射正確,一切工作正常,我可以使用標準API檢索兩個實體。
@Entity
public class UserResearch extends ManagedEntity {
@ManyToOne
@JoinColumn(name = "research_id")
private Research research;
@Entity
public class Research extends ManagedEntity {
@OneToMany(mappedBy = "research")
private Set<UserResearch> userResearches = new HashSet<UserResearch>(0);
您是否嘗試過使用其他Collection接口,例如'List'?這個問題可能不在查詢本身,因爲它看起來很合理,但我不能把它放在手邊。 – kostja