java - jpa 本机查询控制实体（第 2 部分）

Question

续。在jpa 本机查询上检索多个实体

• 我的数据库（测试）
  

  company - ID {PK}, name
  staff - ID{PK}, name, companyID{FK}
  department - ID{PK}, name, companyID{FK}, staffID{FK}
  project - ID{PK}, name, staffID{FK}
  

• 首先，我要备份company表。

  String query = "SELECT c.ID as companyid, c.name as companyname FROM company c";
  Query q = em.createNativeQuery(query, "MAPPING");
  List<CompanyDTO> list = q.getResultList();
  
  Company.java
  @SqlResultSetMapping(name = "MAPPING", classes = {
  @ConstructorResult(
      targetClass = CompanyDTO.class,
      columns = {
          @ColumnResult(name = "companyid"),
          @ColumnResult(name = "companyname")
      })
  })
  ...
  

• 其次，我要备份staff表。

  String query = "SELECT s.ID as staffid, s.name as staffname, s.companyID as companyID 
                  FROM staff s JOIN company c ON c.ID = s.companyID";
  Query q = em.createNativeQuery(query, "MAPPING");
  List<CompanyDTO> list = q.getResultList();
  
  Company.java
  @SqlResultSetMapping(name = "MAPPING", classes = {
  @ConstructorResult(
      targetClass = CompanyDTO.class,
      columns = {
          @ColumnResult(name = "staffid"),
          @ColumnResult(name = "staffname"),
          @ColumnResult(name = "companyID")
      })
  })
  ...
  

• 现在我不想修理我的桌子和班级。我该如何控制？从以下？

  SELECT ... FROM ? 
  List<?> list = q.getResultList();
  

  任何帮助请...