IDCard類里主鍵是
@Id
@EmbeddedId
private StudentPK studentPK;
Student類里IDCard的關聯(lián):
@OneToOne(cascade = CascadeType.ALL)
@JoinColumns(
{
@JoinColumn(name = "id"),
@JoinColumn(name = "sid")
}
)
private IDCard idCard;
@Id
@EmbeddedId
private StudentPK studentPK;
Student類里IDCard的關聯(lián):
@OneToOne(cascade = CascadeType.ALL)
@JoinColumns(
{
@JoinColumn(name = "id"),
@JoinColumn(name = "sid")
}
)
private IDCard idCard;
2018-05-15
FetchType.LAZY:懶加載,加載一個實體時,定義懶加載的屬性不會馬上從數(shù)據(jù)庫中加載。
FetchType.EAGER:急加載,加載一個實體時,定義急加載的屬性會立即從數(shù)據(jù)庫中加載。
FetchType.EAGER:急加載,加載一個實體時,定義急加載的屬性會立即從數(shù)據(jù)庫中加載。
2018-04-06