Java id为自动递增使用@GeneratedValue注释如果与PostgreSQL不同，则使用此注释，其中name_seq为序列名

，实体

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int filmId;
    @Column(name="title")
    private String title;
    @Column(name="description")
    private String Description;
    @Column(name="release_year")
    private String releaseYear;
    @NaturalId
    private int languageId;
    @NaturalId
    @Column(name="original_languageId", nullable=true)
    private Integer originalLanguageId;
    @Column(name="rental_duration")
    private int rentalDuration;
    @Column(name="rental_rate")
    private float rentalRate;
    @Column(name="length")
    private int length;
    @Column(name="replacement_cost")
    private float replacementCost;
    @Column
    private String rating;
    @Column(name="special_features")
    private String specialFeatures;
    @Column(name="last_update")
    private Timestamp lastUpdate;  

更新查询以匹配Film类中的属性名称，如下所示：

---

您应该测试

文件

类中的属性是否类似于

租金

而不是

租金

所以在JPA中，我们使用类中的属性名称，而不是数据库中的列名称

更新实体类并使用数据库中的名称使用

@Column

注释，您可以使用与java约定相关的任何名称并在JPA中使用它

检查您的id是否为自动递增使用

@GeneratedValue

注释如果与PostgreSQL不同，请使用此注释，其中

name_seq

是序列名

，实体

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int filmId;
    @Column(name="title")
    private String title;
    @Column(name="description")
    private String Description;
    @Column(name="release_year")
    private String releaseYear;
    @NaturalId
    private int languageId;
    @NaturalId
    @Column(name="original_languageId", nullable=true)
    private Integer originalLanguageId;
    @Column(name="rental_duration")
    private int rentalDuration;
    @Column(name="rental_rate")
    private float rentalRate;
    @Column(name="length")
    private int length;
    @Column(name="replacement_cost")
    private float replacementCost;
    @Column
    private String rating;
    @Column(name="special_features")
    private String specialFeatures;
    @Column(name="last_update")
    private Timestamp lastUpdate;  

更新查询以匹配Film类中的属性名称，如下所示：

---

---

电影中是否有名为

rental\u rate

的属性？@sc0der文件是什么意思？我指的是电影实体，类中名为

rental\u rate

的属性是否存在？是的，我在DB上测试了查询，结果正常。我只是不明白为什么它不在代码中。可能是hibernate中硬编码的东西？我知道DB col可能被称为

rental\u rate

，但在课堂上你是像

rentalRate

或

rental\u rate

那样声明的吗？你在电影中有名为

rental\u rate

的属性吗？@sc0der你所说的文件是什么意思？我指的是电影实体，类中名为

rental\u rate

的属性是否存在？是的，我在DB上测试了查询，结果正常。我只是不明白为什么它不在代码中。可能是hibernate中硬编码的东西？我知道DB col可能被称为

rental\u rate

，但在课堂上你是否像

rentalRate

或

rental\u rate

一样声明了它，我知道并测试了其他查询和工作。这一个给我带来了未知的实体你能在你的问题中加入

Film

class吗好的，所以DB中的列在单词之间使用下划线，比如“租金”？是的，这一列和另一列我也需要。我不能更改他们的名字。我知道并测试其他查询和工作。这一个给我带来了未知的实体你能在你的问题中加入

Film

class吗好的，所以DB中的列在单词之间使用下划线，比如“租金”？是的，这一列和另一列我也需要。我不能改变他们的名字。

Caused by: org.hibernate.HibernateException: Errors in named queries: Film.prices

@Entity
@Table(name="film")
@NamedQueries({
    @NamedQuery(name = "Film.findAll", query = "SELECT f FROM Film f")
   ,@NamedQuery(name = "Film.findById", query = "SELECT f FROM Film f WHERE f.filmId=:filmId")
   ,@NamedQuery(name = "Film.ratings", query = "SELECT f.rating FROM Film f")
   //,@NamedQuery(name = "Film.prices", query = "SELECT f.rental_rate FROM Film f")
})

@NamedNativeQueries({
    @NamedNativeQuery(name = "Film.prices", query = "SELECT f.rental_rate FROM Film f")
})

Caused by: org.hibernate.MappingException: Unknown entity: java.lang.String

@Entity
@Table(name="film")
@NamedQueries({
    @NamedQuery(name = "Film.findAll", query = "SELECT f FROM Film f")
   ,@NamedQuery(name = "Film.findById", query = "SELECT f FROM Film f WHERE f.filmId=:filmId")
   ,@NamedQuery(name = "Film.ratings", query = "SELECT f.rating FROM Film f")
   ,@NamedQuery(name = "Film.prices", query = "SELECT f.rentalRate FROM Film f")
})

/*@NamedNativeQueries({
    @NamedNativeQuery(name = "Film.prices", query = "SELECT f.rentalRate FROM Film f")
})*/
public class Film implements Serializable{
    @Id
    private int filmId;
    private String title;
    private String Description;
    private String releaseYear;
    @NaturalId
    private int languageId;
    @NaturalId
    @Column(nullable=true)
    private Integer originalLanguageId;
    private int rentalDuration;
    private float rentalRate;
    private int length;
    private float replacementCost;
    private String rating;
    private String specialFeatures;
    private Timestamp lastUpdate;    



    @ManyToMany(cascade = CascadeType.ALL , fetch = FetchType.EAGER)
    @JoinTable(
            name = "film_category",
            joinColumns = { @JoinColumn(name = "film_id") },
            inverseJoinColumns = { @JoinColumn(name = "category_id") }
    )
    private Set<Category> categories = new HashSet<Category>();

    @ManyToMany(cascade = CascadeType.ALL , fetch = FetchType.EAGER)
    @JoinTable(
            name = "inventory",
            joinColumns = { @JoinColumn(name = "film_id") },
            inverseJoinColumns = { @JoinColumn(name = "inventory_id") }
    )
    private List<Store> stores = new ArrayList<Store>();


    public int getFilmId() {
        return filmId;
    }

    public void setFilmId(int filmId) {
        this.filmId = filmId;
    }

    public String getTitle() {
        return title;
    }

    public void setTitle(String title) {
        this.title = title;
    }

    public String getDescription() {
        return Description;
    }

    public void setDescription(String Description) {
        this.Description = Description;
    }

    public String getReleaseYear() {
        return releaseYear;
    }

    public void setReleaseYear(String releaseYear) {
        this.releaseYear = releaseYear;
    }

    public int getLanguageId() {
        return languageId;
    }

    public void setLanguageId(int languageId) {
        this.languageId = languageId;
    }

    public int getOriginalLanguageId() {
        return originalLanguageId;
    }

    public void setOriginalLanguageId(int originalLanguageId) {
        this.originalLanguageId = originalLanguageId;
    }

    public int getRentalDuration() {
        return rentalDuration;
    }

    public void setRentalDuration(int rentalDuration) {
        this.rentalDuration = rentalDuration;
    }

    public float getRentalRate() {
        return rentalRate;
    }

    public void setRentalRate(float rentalRate) {
        this.rentalRate = rentalRate;
    }

    public int getLenght() {
        return length;
    }

    public void setLenght(int lenght) {
        this.length = lenght;
    }

    public float getReplacementCost() {
        return replacementCost;
    }

    public void setReplacementCost(float replacementCost) {
        this.replacementCost = replacementCost;
    }

    public String getRating() {
        return rating;
    }

    public void setRating(String rating) {
        this.rating = rating;
    }

    public String getSpecialFeatures() {
        return specialFeatures;
    }

    public void setSpecialFeatures(String specialFeatures) {
        this.specialFeatures = specialFeatures;
    }

    public int getLength() {
        return length;
    }

    public void setLength(int length) {
        this.length = length;
    }

    public Timestamp getLastUpdate() {
        return lastUpdate;
    }

    public void setLastUpdate(Timestamp lastUpdate) {
        this.lastUpdate = lastUpdate;
    }

    public void setCategories(Set<Category> categories) {
        this.categories = categories;
    }

    public Set<Category> getCategories() {
        return this.categories;
    }

    public List<Store> getStores() {
        return stores;
    }

    public void setStores(List<Store> stores) {
        this.stores = stores;
    }

    @Override
    public String toString() {
        return "Film{" + "filmId=" + filmId + ", title=" + title + ", Description=" + Description + ", releaseYear=" + releaseYear + ", languageId=" + languageId + ", originalLanguageId=" + originalLanguageId + ", rentalDuration=" + rentalDuration + ", rentalRate=" + rentalRate + ", length=" + length + ", replacementCost=" + replacementCost + ", rating=" + rating + ", specialFeatures=" + specialFeatures + ", lastUpdate=" + lastUpdate + ", categories=" + categories + '}';
    }
}

    @SequenceGenerator(name="name_seq",
                       sequenceName="name_seq",
                       allocationSize=1)
    @GeneratedValue(strategy = GenerationType.SEQUENCE,
                    generator="name_seq")

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private int filmId;
    @Column(name="title")
    private String title;
    @Column(name="description")
    private String Description;
    @Column(name="release_year")
    private String releaseYear;
    @NaturalId
    private int languageId;
    @NaturalId
    @Column(name="original_languageId", nullable=true)
    private Integer originalLanguageId;
    @Column(name="rental_duration")
    private int rentalDuration;
    @Column(name="rental_rate")
    private float rentalRate;
    @Column(name="length")
    private int length;
    @Column(name="replacement_cost")
    private float replacementCost;
    @Column
    private String rating;
    @Column(name="special_features")
    private String specialFeatures;
    @Column(name="last_update")
    private Timestamp lastUpdate;  

@Entity
@Table(name="film")
@NamedQueries({
    @NamedQuery(name = "Film.findAll", query = "SELECT f FROM Film f")
   ,@NamedQuery(name = "Film.findById", query = "SELECT f FROM Film f WHERE f.filmId=:filmId")
   ,@NamedQuery(name = "Film.ratings", query = "SELECT f.rating FROM Film f")
   ,@NamedQuery(name = "Film.prices", query = "SELECT f.rentalRate FROM Film f")
})