java 字段列表中的 JPA 未知列
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JPA Unknown Column in Field List
提问by Malena T
I have a relation between Accommodationand Bookingclasses, and also I set a foreign key in booking table.
我在Accommodation和Booking类之间有关系，并且我在预订表中设置了一个外键。
ALTER TABLE `project`.`booking`
ADD INDEX `fk_accId_fk_idx` (`accommodation` ASC);
ALTER TABLE `project`.`booking`
ADD CONSTRAINT `fk_accId_fk`
FOREIGN KEY (`accommodation`)
REFERENCES `project`.`accommodation` (`id`)
ON DELETE NO ACTION
ON UPDATE NO ACTION;
Accommodation class:
住宿等级：
@Entity
....
public class Accommodation implements Serializable {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id", unique = true, nullable = false)
private BigInteger id;
@OneToMany(mappedBy = "accommodation", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
@JsonManagedReference
private List < Booking > bookings;
......getters setters
}
Booking class:
预订舱位：
@Entity
public class Booking implements Serializable {
......
@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = "bookings", nullable = true)
@JsonBackReference
private Accommodation accommodation;
....getters setters
}
When I execute a query for listing accommodations, I get unknown column in field list error.
当我执行列出住宿的查询时，我在字段列表错误中得到未知列。
javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: could not extract ResultSet] with root cause com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'bookings7_.bookings' in 'field list'
javax.persistence.PersistenceException: org.hibernate.exception.SQLGrammarException: 无法提取 ResultSet] 与根本原因 com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: 'field list' 中的未知列 'bookings7_.bookings'
Even I set the relation and define the foreign key in table, what is the reason that I get this error?
即使我设置了关系并在表中定义了外键，我收到此错误的原因是什么？
回答by XiCoN JFS
Try to define your join-table mapping manually in JPA. Drop your schema and let JPA create your tables:
尝试在 JPA 中手动定义连接表映射。删除您的架构并让 JPA 创建您的表：
Accommodation class
住宿等级
@OneToMany(mappedBy = "accommodation", fetch = FetchType.EAGER, cascade = CascadeType.REMOVE)
@JsonManagedReference
private List < Booking > bookings;
Booking class
预订舱位
@ManyToOne(fetch = FetchType.EAGER)
@JoinTable(name = "accommodation_booking_join_table",
joinColumns = {@JoinColumn(name="booking_id")},
inverseJoinColumns = @JoinColumn(name = "accommodation_id"))
@JsonBackReference
private Accommodation accommodation;
回答by Hussain Ali
Try changing your column names to lower case in your db and entity class.
尝试在数据库和实体类中将列名更改为小写。
回答by Lekso Pozuaho
I had a situation like that, and I solved it by changing the field's position on the query. Looks like it's a MySQL bug, like (or the same as) the one mentioned on this post:
我遇到过这样的情况，我通过更改字段在查询中的位置来解决它。看起来这是一个 MySQL 错误，就像（或与）这篇文章中提到的错误一样：
https://bugs.mysql.com/bug.php?id=1689
https://bugs.mysql.com/bug.php?id=1689
The description of this MySQL bug mentioned a similar workaround solution: "I found that by swapping that field's position in the table with another field that it worked OK."
这个 MySQL 错误的描述提到了一个类似的解决方法：“我发现通过将该字段在表中的位置与另一个工作正常的字段交换。”
