Question

@Column(name = "userId")
    @UniqueConstraint
    private Integer userId;

I am using these annotation for entering data into database table. i want to make userId field unique field. but when i am doing like it it is showing me error @UniqueConstraints is disallowed for this location.

Answer 1

@Column(name = "userId",unique=true)

http://docs.jboss.org/hibernate/annotations/3.5/vis/en/html_single/#entity-mapping-identifier”rel=“noreferer” 你也可以这样做。

    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    private Integer id;

Answer 2

Here s an example of how to use @UniqueConstraint:

@Entity
@Table(name = "contact", 
  uniqueConstraints = @UniqueConstraint(columnNames = {"name", "company_id"}))
public class Contact {
  ...
}

This specifies that the combination of the "name" column and the "company_id" column will be unique.

Answer 3

https://docs.jbos.org/hibernate/annotations/3.5/vis/en/html_single/#entity-mapping-entity”rel=“noreferer”>Hibernate doc,第3.5版@UniqueConstraint

 @Entity
    @Table(name="tbl_sky",uniqueConstraints = {@UniqueConstraint(columnNames={"month", "day"})})
    public class Sky implements Serializable {
       ...
    }

http://docs.jbos.org/hibernate/orm/4.3/manual/en-US/html/ch05.html#mapping-declaration-class”rel=“noreferer”

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