一对多

单向

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "xx_order_item_rel", joinColumns = {@JoinColumn(name = "oir_id")}, inverseJoinColumns = {@JoinColumn(name = "p_id")})

双向

订单

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "xx_order_item_rel", joinColumns = {@JoinColumn(name = "oir_id")})

商品

@OneToMany(mappedBy = "p_id", fetch = FetchType.LAZY)

多对多

@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "t_office_rel_group", joinColumns = @JoinColumn(name = "group_id"), inverseJoinColumns = @JoinColumn(name = "office_id"))
    
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name = "t_office_rel_group", joinColumns = @JoinColumn(name = "office_id"), inverseJoinColumns = @JoinColumn(name = "group_id"))