初始化Go学习项目

go-gorm-demo/association_methods.go

@@ -0,0 +1,71 @@
+package main
+
+import (
+	"fmt"
+
+	"gorm.io/driver/sqlite"
+	"gorm.io/gorm"
+)
+
+//type User struct {
+//	ID     uint   `gorm:"primaryKey"`
+//	Name   string `gorm:"size:100"`
+//	Orders []Order
+//}
+//
+//type Order struct {
+//	ID      uint `gorm:"primaryKey"`
+//	UserID  uint
+//	Product string `gorm:"size:100"`
+//	Amount  int
+//}
+
+func main() {
+	db, _ := gorm.Open(sqlite.Open("test.db"), &gorm.Config{})
+	db.AutoMigrate(&User{}, &Order{})
+
+	//user := User{Name: "Alice"}
+	//db.Create(&user)
+
+	//查询用户根据名称
+	var user User
+	db.Where("name = ?", "Alice").First(&user)
+
+	//order1 := Order{Product: "Laptop"}
+	//order2 := Order{Product: "Mouse"}
+	//order3 := Order{Product: "Keyboard"}
+
+	// 1. Append - 添加关联
+	//db.Model(&user).Association("Orders").Append(&order1, &order2)
+	//fmt.Println("Orders appended")
+
+	// 2. Count - 统计关联数量
+	//count := db.Model(&user).Association("Orders").Count()
+	//fmt.Printf("Order count: %d\n", count)
+
+	// 4. Replace - 替换所有关联
+	//db.Model(&user).Association("Orders").Replace(&order3)
+
+	//查询订单 Keyboard
+	var order3 Order
+	db.Where("product = ?", "Keyboard").First(&order3)
+
+	// 5. Delete - 删除关联（不删除记录本身）
+	//db.Model(&user).Association("Orders").Delete(&order3)
+	//fmt.Println("Association deleted")
+
+	//fmt.Println("Orders replaced with Keyboard")
+
+	// 6. Clear - 清空所有关联
+	//db.Model(&user).Association("Orders").Append(&order3)
+	db.Model(&user).Association("Orders").Clear()
+	fmt.Println("All associations cleared")
+
+	// 3. Find - 查找关联
+	var orders []Order
+	db.Model(&user).Association("Orders").Find(&orders)
+	fmt.Println("Orders found:")
+	for _, o := range orders {
+		fmt.Printf("  - %s\n", o.Product)
+	}
+}