JPQL中有这种CASE表达式吗？

Question

假设有一张桌子：

TableA:Field1, Field2, Field3

和关联的JPA实体类

@Entity
@Table(name="TableA")
public class TableA{
  @Id
  @Column(name="Field1")
  private Long id;

  @Column(name="Field2")
  private Long field2;

  @Column(name="Field3")
  private Long field3;

  //... more associated getter and setter...
}

有什么方法可以构造松散地转换为该SQL的JPQL语句，即如何将case表达式转换为JPQL？

select field1,
case
  when field2 = 1 then 'One'
  when field2 = 2 then 'Two'
  else 'Other number'
end,
field3
from tableA;

Answer 1

它已在JPA 2.0中添加

用法：

SELECT e.name, CASE WHEN (e.salary >= 100000) THEN 1 WHEN (e.salary < 100000) THEN 2 ELSE 0 END FROM Employee e

参考： http

:
//en.wikibooks.org/wiki/Java_Persistence/JPQL_BNF#New_in_JPA_2.0