而不是寫
.filter(tableADao -> tableADao.tableBDaos().isEmpty())
我正在尋找撰寫一個 postgreSQL 查詢來洗掉空集合。我想我需要寫一個連接，然后是 IS NOT EMPTY。這個怎么寫？
在表中 AI 有
@Id
@Column(name = "id_pop", nullable = false)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
@OneToMany(mappedBy = "tableADao", cascade = CascadeType.ALL, orphanRemoval = true)
private Collection<TableBDao> tableBDaos = new ArrayList<>();
在表 BI 中有
@ManyToOne(cascade = CascadeType.ALL)
@JoinColumn(name = "crr_pop_id", nullable = false)
private TableADao tableADao;
uj5u.com熱心網友回復：
嘗試
select * from A a
where 0 < (select count(*) from B b where a.id_pop = b.crr_pop_id )
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標籤：爪哇 PostgreSQL jpa
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