> 本章介紹多對多關系（many to many） [TOC] ## 多對多關系（many to many） ~~~ // User 包含并屬于多個 languages, 使用 `user_languages` 表連接 type User struct { gorm.Model Languages []Language `gorm:"many2many:user_languages;"` } type Language struct { gorm.Model Name string } db.Model(&user).Related(&languages, "Languages") // SELECT * FROM "languages" INNER JOIN "user_languages" ON "user_languages"."language_id" = "languages"."id" WHERE "user_languages"."user_id" = 111 ~~~ ## 指定外鍵 ~~~ type CustomizePerson struct { IdPerson string `gorm:"primary_key:true"` Accounts []CustomizeAccount `gorm:"many2many:PersonAccount;ForeignKey:IdPerson;AssociationForeignKey:IdAccount"` } type CustomizeAccount struct { IdAccount string `gorm:"primary_key:true"` Name string } ~~~