select c.comp_name from company c where c.cid = (select cid from com_usr_rel where uid=1100)

@Entity

public class Company implements Serializable {
   private static final long serialVersionUID = 1L;

   @Id
   @GeneratedValue(strategy=GenerationType.AUTO)
   @Column(name="company_id")
   private String companyId;

   @Column(name="apartment_no")
   private BigDecimal apartmentNo;

   private String city;

   @Column(name="company_name")
   private String companyName;

   //bi-directional many-to-one association to CompanyUser
   @OneToMany(mappedBy="company")
   private List<CompanyUser> companyUsers;

    public Company() {
    }

   public String getCompanyId() {
      return this.companyId;
   }

   public void setCompanyId(String companyId) {
      this.companyId = companyId;
   }

   public BigDecimal getApartmentNo() {
      return this.apartmentNo;
   }

   public void setApartmentNo(BigDecimal apartmentNo) {
      this.apartmentNo = apartmentNo;
   }

   public String getCity() {
      return this.city;
   }

   public void setCity(String city) {
      this.city = city;
   }

   public String getCompanyName() {
      return this.companyName;
   }

   public void setCompanyName(String companyName) {
      this.companyName = companyName;
   }
   
   public List<CompanyUser> getCompanyUsers() {
      return this.companyUsers;
   }

   public void setCompanyUsers(List<CompanyUser> companyUsers) {
      this.companyUsers = companyUsers;
   }}

@Entity
@Table(name="com_usr_rel")
public class CompanyUser implements Serializable {
   private static final long serialVersionUID = 1L;

   @Id
   @GeneratedValue(strategy=GenerationType.AUTO)
   @Column(name="com_usr_rel_id")
   private String comUserId;

   //bi-directional many-to-one association to Company
    @ManyToOne
   @JoinColumn(name="company_id")
   private Company company;

   //bi-directional many-to-one association to User
    @ManyToOne
   @JoinColumn(name="user_id")
   private User user;

    public CompanyUser() {
    }

   public String getCom_usr_relId() {
      return this.comUserId;
   }

   public void setCom_usr_relId(String com_usr_relId) {
      this.comUserId = comUserId;
   }

   public Company getCompany() {
      return this.company;
   }

   public void setCompany(Company company) {
      this.company = company;
   }
   
   public User getUser() {
      return this.user;
   }

   public void setUser(User user) {
      this.user = user;
   }
}