Hibernate報錯：On release of batch it still contained JDBC statements

錯誤現象：Project和User使用註解多對一單向關聯(@ManyToOne)

    // Project 類
    @ManyToOne
    @JoinColumn(name = "user_id", nullable = false)
    private User user;

先new一個Project對象，並從數據庫中取出User對象放入Project對象

此時使用session.save(project)報錯：On release of batch it still contained JDBC statements

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錯誤分析：由於user對象是從數據庫中取出，還緩存在session中，此時save(project)就報錯

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解決辦法：配置Cascade註解就可以了

    @ManyToOne
    @Cascade(value = CascadeType.SAVE_UPDATE) // 增加該註解即可
    @JoinColumn(name = "user_id", nullable = false)
    private User user;

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解決辦法二：用session.merge() 方法代替session.save() 即可