> 本章介紹一對多關系（has many） [TOC] ## 一對多關系（has many） ~~~ // User 包含多個 emails, UserID 為外鍵 type User struct { gorm.Model Emails []Email } type Email struct { gorm.Model Email string UserID uint } db.Model(&user).Related(&emails) // SELECT * FROM emails WHERE user_id = 111; // 111 是 user 的主鍵 ~~~ ## 指定外鍵 ~~~ type Profile struct { gorm.Model Name string UserRefer uint } type User struct { gorm.Model Profiles []Profile `gorm:"ForeignKey:UserRefer"` } ~~~ ## 指定外鍵和關聯外鍵 ~~~ type Profile struct { gorm.Model Name string UserID uint } type User struct { gorm.Model Refer string Profiles []Profile `gorm:"ForeignKey:UserID;AssociationForeignKey:Refer"` } ~~~