在golang中扫描SQL空值

package main

import (
	"database/sql"
	"fmt"

	_ "github.com/go-sql-driver/mysql"
)

type User struct {
	ID   int
	Name sql.NullString
	Age  sql.NullInt64
}

func main() {
	db, err := sql.Open("mysql", "username:password@tcp(localhost:3306)/database")
	if err != nil {
		fmt.Println("Failed to connect to database:", err)
		return
	}
	defer db.Close()

	rows, err := db.Query("SELECT id, name, age FROM users")
	if err != nil {
		fmt.Println("Failed to execute query:", err)
		return
	}
	defer rows.Close()

	var users []User
	for rows.Next() {
		var user User
		err := rows.Scan(&user.ID, &user.Name, &user.Age)
		if err != nil {
			fmt.Println("Failed to scan row:", err)
			continue
		}
		users = append(users, user)
	}

	if err := rows.Err(); err != nil {
		fmt.Println("Error occurred during iteration:", err)
		return
	}

	for _, user := range users {
		if user.Name.Valid {
			fmt.Println("Name:", user.Name.String)
		} else {
			fmt.Println("Name is NULL")
		}

		if user.Age.Valid {
			fmt.Println("Age:", user.Age.Int64)
		} else {
			fmt.Println("Age is NULL")
		}

		fmt.Println("-----")
	}
}