@GeneratedValue polymorphic abstract superclass over MySQL

In a Spring MVC application using Hibernate and MySQL, I have an abstract superclass `BaseEntity` that manages the values of the IDs for all the other entities in the model. The `id` field uses `@GeneratedValue`. I am encountering a problem whenever my code tries to save any of the subclasses that extend `BaseEntity`. The problem comes with the choice of `GenerationType` for the `@GeneratedValue`. At every place in my code where a subclass of `BaseEntity` tries to save to the underlying MySQL database, I get the following error: ``` ERROR SqlExceptionHelper - Table 'docbd.hibernate_sequences' doesn't exist ``` I have read many postings about this on SO and on google, but they either deal with other databases (not MySQL) or they do not deal with abstract superclasses. I cannot solve the problem by using `GenerationType.IDENTITY` because I am using an abstract superclass to manage `id` fields for all entities in the model. Similarly, I cannot use `GenerationType.SEQUENCE` because MySQL does not support sequences. So how do I solve this problem? Here is the code for `BaseEntity.java`: ``` @Entity @Inheritance(strategy = InheritanceType.TABLE_PER_CLASS) public abstract class BaseEntity { @Id @GeneratedValue(strategy = GenerationType.TABLE) protected Integer id; public void setId(Integer id) {this.id = id;} public Integer getId() {return id;} public boolean isNew() {return (this.id == null);} } ``` Here is an example of the code for one of the entities that extends `BaseEntity`: ``` @Entity @Table(name = "ccd") public class CCD extends BaseEntity{ //other stuff } ``` Here is the DDL: ``` CREATE TABLE IF NOT EXISTS ccd( id int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY, #other stuff )engine=InnoDB;SHOW WARNINGS; ``` Here is the JPQL code in the DAO: ``` @Override @Transactional public void saveCCD(CCD ccd) { if (ccd.getId() == null) { System.out.println("[[[[[[[[[[[[ about to persist CCD ]]]]]]]]]]]]]]]]]]]]"); this.em.persist(ccd); this.em.flush(); } else { System.out.println("]]]]]]]]]]]]]]]]]] about to merge CCD [[[[[[[[[[[[[[[[[[[[["); this.em.merge(ccd); this.em.flush(); } } ``` EDIT: The reason I cannot use `@MappedSuperClass` in this situation is that I need to have `ManyToOne` relationships that allow for multiple subtypes to be used interchangeably. Look at the `AccessLog` class below as an example. It has an `actor_entity` and a `target_entity`. There can be many types of actor entities and many types of target entities, but they all inherit from `BaseEntity`. This inheritance enables the underlying `accesslogs` data table in MySQL to just have one `actor_entity_id` field and just one `target_entity_id` field instead of having to have several fields for each. When I change `@Entity` above `BaseEntity` to `@MappedSuperClass`, a different error gets thrown indicating that `AccessLog` cannot find `BaseEntity`. `BaseEntity` needs `@Entity` annotation in order for `AccessLog` to have polymorphic properties. ``` @Entity @Table(name = "accesslogs") public class AccessLog extends BaseEntity{ @ManyToOne @JoinColumn(name = "actorentity_id") private BaseEntity actor_entity; @ManyToOne @JoinColumn(name = "targetentity_id") private BaseEntity target_entity; @Column(name="action_code") private String action; //getters, setters, & other stuff } ``` SECOND EDIT: As per JBNizet's suggestion, I created a hibernate_sequences table as follows: ``` CREATE TABLE IF NOT EXISTS hibernate_sequences( sequence_next_hi_value int(11) UNSIGNED NOT NULL AUTO_INCREMENT PRIMARY KEY )engine=InnoDB;SHOW WARNINGS; ``` But now I am getting the following error: ``` Caused by: com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'sequence_name' in 'where clause' ``` Here is the hibernate sql causing the error, followed by the next 2 lines of the stack trace: ``` Hibernate: select sequence_next_hi_value from hibernate_sequences where sequence_name = 'BaseEntity' for update ERROR MultipleHiLoPerTableGenerator - HHH000351: Could not read or init a hi value com.mysql.jdbc.exceptions.jdbc4.MySQLSyntaxErrorException: Unknown column 'sequence_name' in 'where clause' ``` How do I resolve this?