使用JPA

Question

寫一個請求

如何使用JPA請求通過給定的平臺名稱檢索環境名稱（1個環境可以關聯到n Plateform和1 Platform可以關聯到n Environmnt）？

public class HPe implements Serializable { 
private static final long serialVersionUID = 1L; 
@EmbeddedId 
protected HPePK hPePK; 
@Column(name = "PE_TIMEOUT") 
private Integer peTimeout; 
@Column(name = "PE_STATUS") 
private Boolean peStatus; 
@OneToMany(cascade = CascadeType.ALL, mappedBy = "hPe") 
private Collection<HPesp> hPespCollection; 
@JoinColumn(name = "PE_ENV", referencedColumnName = "ENV_URL", insertable = false, updatable = false) 
@ManyToOne(optional = false) 
private HEnv hEnv; // HEnv classe name 
@JoinColumn(name = "PE_PLATFORM", referencedColumnName = "PLATFORM_NAME", insertable = false, updatable = false) 
@ManyToOne(optional = false) 
private HPlatform hPlatform; //HPlatform classe name 
} 

更新 問題Resloved：

SELECT h.hPePK.peEnv FROM HPE H其中h.hPePK.pePlatform =：W

Answer 1

請嘗試

select hpe.hEnv.envName from HPe hpe where hpe.hPlatform.platName = :platName 

（使用platName作爲參數）

也許它需要更多的東西ike a join但是請先嚐試