@UniqueConstraints失敗的更新

我有，我把的UniqueConstraint註解@UniqueConstraints失敗的更新

@Table(uniqueConstraints={@UniqueConstraint(columnNames={"staffRecord_id", "defaultLabel_id","company_id","keyCode"})}) 
public class AllowanceDeduction implements Serializable{ 
---

我已經注意到了，就是當我嘗試以節省使用

if (allowanceDeduction.getId() == null) { 
      this.entityManager.persist(allowanceDeduction); 
     } else { 

      this.entityManager.merge(allowanceDeduction); 
     } 


when the save or update fails due to a unique constraint. Isn't it only supposed to fail when trying to save a new record that is identical to a record that already exist.

爲什麼表一個實體類嘗試合併或更新時會失敗嗎？請幫助需要

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2011-08-08 Chinedu

我不能肯定地說，但它看起來像你想堅持一個空ID

if (allowanceDeduction.getId() == null) { 
     this.entityManager.persist(allowanceDeduction); 
     /* don't you need the id set to a non-null value in order to persist it? */ 
    } else {

來源

2011-08-09 13:51:53 Luke

@UniqueConstraints失敗的更新

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