检索涉及多个关节的数据的标准

Question

我有四个表，其中的示例数据如下所示

员工

EMP_ID|EMP_NAME
---------------
101   |John

EmployeeDtl

EMP_DTL_ID  |EMP_SKILLS |EMP_ID
-----------------------------------
1001        |Java       |101
1002        |SQL        |101

EmpDeptDtl

EMP_DTL_ID  |DEPT_ID
--------------------
1001        |22
1002        |33

部门

DEPT_ID |DEPT_NAME
----------------------
22      |XYZ
33      |PQR

下面是我对应的pojos

@Entity
public class Employee {
   private static final long serialVersionUID = 1L;

   @Id
   @Column(name="EMP_ID")
   private Long empId;

   @Column(name="EMP_NAME")
   private String empName;

   //bi-directional many-to-one association to EmployeeDtl 
   @OneToMany(mappedBy="employee", cascade=CascadeType.ALL, fetch=FetchType.EAGER)
   private Set<EmployeeDtl> empDtls;


@Entity
@Table(name="EMP_DTL")
public class EmployeeDtl {

   @Id
   @Column(name="EMP_DTL_ID")
   private Long empDtlId;

   @Column(name="EMP_GRP")
   private String employeeGrp;


   //bi-directional many-to-one association to Employee 
    @ManyToOne
   @JoinColumn(name="EMP_ID")
   private Employee employee;

    @Column(name="EMP_ID", insertable=false, updatable=false)
   private Long empId;

   //bi-directional many-to-one association to EmpDeptDtl
   @OneToMany(mappedBy="id.empDtlId", cascade= CascadeType.ALL)
   private Set<EmpDeptDtl> empDeptDtls;



@Entity
public class EmpDeptDtl {

   @EmbeddedId
   private EmpDeptDtlPK id;

   @Column(name="EMP_DTL_ID", insertable = false, updatable = false)
   private Long empDtlId;

   //bi-directional many-to-one association to Dept
    @ManyToOne(fetch=FetchType.LAZY)
   @JoinColumn(name="DEPT_ID", insertable = false, updatable = false)
   private Dept deptId;



@Embeddable
public class EmpDeptDtlPK implements Serializable {
   //default serial version id, required for serializable classes.
   private static final long serialVersionUID = 1L;

   @Column(name="DEPT_ID")
   private Long deptId;

   //bi-directional many-to-one association to EmpDeptDtl
    @ManyToOne(fetch=FetchType.LAZY)
   @JoinColumn(name="EMP_DTL_ID")
   private EmployeeDtl employeeDtl;


@Entity
public class Dept  {

   @Id
   @Column(name = "DEPT_ID")
   private Long deptId;

   @Column(name = "DEPT_NAME")
   private String deptName;

        // bi-directional many-to-one association to EmpDeptDtl 
   @OneToMany(mappedBy = "deptId")
   private Set<EmpDeptDtl> empDeptDtls;

现在，谁能建议我如何使用 CRITERIA 检索给定 EMP_ID 的部门记录列表。在上面给出的示例数据中，对于 EMP_ID=101，应返回 dept_ids 为 22 和 33 的部门记录。

我使用命名查询和原生 SQl 查询获得了解决方案。但我无法通过休眠标准得到它。有人可以帮我吗？

谢谢 哈里什

Answer 1

这是从 .net 到 java 的直接翻译，我不确定语法是否正确，但您可以围绕它进行操作（不确定，因为从外观上看，您似乎不太了解 abt 标准，我建议阅读 abt 它，因为这是最容易编写的查询之一）

session.createCriteria(Employee.class,"emp")
.createAlias("emp.empDtls","empDetail")
.createAlias("empDetail.empDeptDtls","empDetail")
.createAlias("empDetail.deptId","dept")
.add(Restrictions.Eq("emp.empId", 101))
.setProjection(projections.property("dept.deptId"))
.toList<long>();

答案并不一定意味着我同意你的数据模型。还有一些成员名称可以更改以表示它们真正代表的内容..