I ever posted a same question before. I use the composite primary key for my class

@Entity
@Table(name="group_members")
@IdClass(MembershipPK.class)
public class Membership implements Serializable {

 private long groupId;
 private long personId;

 public Membership() {}

 @Id
 @Column(name="GROUP_ID", nullable = false, insertable = false, updatable = false)
 public long getGroupId() {return groupId;}
 public void setGroupId(long groupId) {this.groupId = groupId;}

 @Id
 @Column(name="PERSON_ID")
 public long getPersonId() {return personId;}
 public void setPersonId(long personId) {this.personId = personId;}
}

@Embeddable
public class MembershipPK implements Serializable{

 private long groupId;
 private long personId;

 public MembershipPK() {}

 public MembershipPK(long groupId, long personId) {
 this.groupId = groupId;
 this.personId = personId;
 }

 public long getGroupId() {return groupId;}
 public void setGroupId(long groupId) {this.groupId = groupId;}

 public long getPersonId() {return personId;}
 public void setPersonId(long personId) {this.personId = personId;}
}

When I tried the sql "select g from Membership g ", I always got an exception: Unknown column 'membership0_.personId' in 'field list'
After I checked the log file, I found the transfered sql is:

[org.hibernate.hql.ast.HqlSqlWalker] processQuery() :
( SELECT ( {select clause} (membership0_.personId, membership0_.groupId) ) ( FromClause{level=1} group_members membership0_ ) )

It seems the system could not get the column PERSON_ID, which was annotated in class, and it always got the class attribute personId. I checked internet examples, and it seems there is no error in my codes. Can JBoss experts give an answer? Thank you in advance.

GUS