java - 如何使用java + hibernate将值插入SQL Server中的主键？

Question

尝试使用 hibernate 运行此 java 代码时收到此错误消息:

create table EMPLOYEE (
    ID integer not null,
    JOINING_DATE date not null,
    NAME varchar(50) not null,
    SALARY decimal(10,2) not null,
    SSN varchar(255) not null,
    primary key (ID)
)

我的Java代码如下所示，使用hibernate，我需要将值插入数据库。

@Entity
@Table(name="EMPLOYEE")
public class Employee {

    @Id
    @Column(name = "ID", nullable = false, insertable = false, updatable = false)
    @TableGenerator(name="ID" ,table="EMPLOYEE", allocationSize=1, initialValue=1)
    private int id;

    @Size(min=3, max=50)
    @Column(name = "NAME", nullable = false)
    private String name;

但是在插入值时出现以下错误:

threw exception [Request processing failed; nested exception is org.springframework.dao.DataIntegrityViolationException: could not execute statement; SQL [n/a]; constraint [null]; nested exception is org.hibernate.exception.ConstraintViolationException: could not execute statement] with root cause
com.microsoft.sqlserver.jdbc.SQLServerException: Violation of PRIMARY KEY constraint 'PK__EMPLOYEE__3214EC27B6653156'. Cannot insert duplicate key in object 'dbo.EMPLOYEE'. The duplicate key value is (0).
    at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDatabaseError(SQLServerException.java:197)
    at com.microsoft.sqlserver.jdbc.SQLServerStatement.getNextResult(SQLServerStatement.java:1493)
    at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement.doExecutePreparedStatement(SQLServerPreparedStatement.java:390)
    at com.microsoft.sqlserver.jdbc.SQLServerPreparedStatement$PrepStmtExecCmd.doExecute(SQLServerPreparedStatement.java:340)
    at com.microsoft.sqlserver.jdbc.TDSCommand.execute(IOBuffer.java:4575)
    at com.microsoft.sqlserver.jdbc.SQLServerConnection.executeCommand(SQLServerConnection.java:1400)
    at com.microsoft.sqlserver.jdbc.SQLServerStatement.executeCommand(SQLServerStatement.java:179)
    at  

Answer 1

创建表时，您应指示 ID 列是主键，并且数据库应控制分配该值:

 id integer NOT NULL IDENTITY PRIMARY KEY,

我对@TableGenerator注解不太熟悉，更常见的方法是用以下方式注解id字段:

@GeneratedValue(strategy = javax.persistence.GenerationType.IDENTITY)

IDENTITY Indicates that the persistence provider must assign primary keys for the entity using a database identity column. More information...

从而让Hibernate知道该字段的值是由数据库控制的。

我希望这会有所帮助。