使用对Postgresql的java查询无法获取null值

Question

在存储库中查询：

 @Query("SELECT r.type AS roomType, r.name AS roomName, r.number AS roomNumber, MIN(mm.doubleValue) AS startValue 
         FROM Measurement AS mm 
         LEFT JOIN mm.meter AS m 
         LEFT JOIN m.room AS r ...)
    methodNameRepository(String name, ...){}

输出：我得到所有非空字段的所有对象：

[
  {
    "roomType": "FLAT",
    "roomNumber": 1,
    "roomName": "Flat",
    "startValue": 20,
    "endDate": "2022-07-01T20:59:00",
    "endValue": 23
  },
  ...
]

我必须获得具有一些空字段的对象，如下所示：

[
  {
    "roomType": "FLAT",
    "roomNumber": 1,
    "roomName": "Flat",
    "startValue": null,
    "endDate": "2022-07-05T20:59:00",
    "endValue": 28
  },
  {
    "roomType": "FLAT",
    "roomNumber": 1,
    "roomName": "Flat",
    "startValue": null,
    "endDate": "2022-07-12T20:59:00",
    "endValue": null
  },
  ...
]

Answer 1

找不到douleValue列中包含空值的行，因为MIN函数不考虑空值。

这个问题的可能解决方案：如何在最小值或最大值中包含空值？