JPA entity has no primary key?

I have an Entity class:

@Entity
@Table(name="CMC_MAP_SERVER_INFO")
@NamedQuery(name="CmcMapServerInfo.getMapServer", query="SELECT c FROM CmcMapServerInfo c")
public class CmcMapServerInfo implements Serializable {
    private static final long serialVersionUID = 1L;

    @Column(name="APPLICATION_NAME")
    private String applicationName;

    private String remarks;

    @Column(name="SERVER_IP")
    private String serverIp;

    @Column(name="SERVER_NAME")
    private String serverName;

    @Column(name="SERVER_PORT")
    private short serverPort;

    public CmcMapServerInfo() {
    }

I get the following error:

Entity class [class cdot.oss.cmsat.conf.ejb.entity.CmcMapServerInfo] has no primary key specified.

I read online and found out that entities must have a primary key defined. But my table here is a ONE row table only. It just used to save system configuration.

So only queries I will like to do will be to check if the row exists then get that row and update it.

My columns are serverIp, port, name of the server.

How should I proceed to remove this error?

JPA 2.0 Specification

• Entity class must be annotated with the Entity annotation.
• Entity class must have a no-arg constructor.
• Entity class must not be final
• Entity class must implement the Serializable interfaces.
• Entity class must have a unique, immutable ID

Otherwise, you cannot.