gorm mysql 表关联的一个例子

package main
import (	"fmt"	"gorm.io/driver/mysql"	"gorm.io/gorm"	"log")
type User struct {	Id       int    `json:"id"`	Name     string `json:"name"`	Age      int    `json:"age"`	ClazzId  int    `json:"clazz_id"`	Clazz    Clazz  `gorm:"foreignKey:ClazzId"`	CreateAt int    `json:"create_at"`}
type Teacher struct {	Id       int    `json:"id"`	Name     string `json:"name"`	Age      int    `json:"age"`	ClazzId  int    `json:"clazz_id"`	CreateAt int    `json:"create_at"`}
type Clazz struct {	Id       int       `json:"id"`	Name     string    `json:"name"`	Number   int       `json:"number"`	CreateAt int       `json:"create_at"`	Teachers []Teacher `gorm:"FOREIGNKEY:ClazzId"`}
func main() {	dsn := "root:aimore123456@tcp(218.91.230.203:23306)/test?charset=utf8mb4&parseTime=True&loc=Local"	db, err := gorm.Open(mysql.Open(dsn), &gorm.Config{})
	if nil != err {		log.Fatal(err)	}
	var user User	if err := db.Preload("Clazz").Preload("Clazz.Teachers").Where("id = ?", 1).First(&user).Error; nil != err {		fmt.Printf("err:%v\n", err)	} else {		fmt.Printf("user:%+v\n", user)	}}

CREATE TABLE `clazzs` (  `id` int NOT NULL AUTO_INCREMENT,  `name` varchar(256) NOT NULL,  `number` int NOT NULL,  `create_at` int NOT NULL,  PRIMARY KEY (`id`));

CREATE TABLE `teachers` (  `id` int NOT NULL AUTO_INCREMENT,  `name` varchar(64) NOT NULL,  `age` int NOT NULL,  `clazz_id` int NOT NULL,  `craete_at` int NOT NULL,  PRIMARY KEY (`id`));

CREATE TABLE `users` (  `id` int NOT NULL AUTO_INCREMENT,  `name` varchar(256) NOT NULL,  `age` int DEFAULT '0',  `create_at` int NOT NULL,  `clazz_id` int NOT NULL,  PRIMARY KEY (`id`));