我们如何在postgres的sqlx中实现批量upsert？

go get github.com/jmoiron/sqlx
go get github.com/lib/pq

import (
    "github.com/jmoiron/sqlx"
    _ "github.com/lib/pq"
)

db, err := sqlx.Connect("postgres", "user=your_user password=your_password dbname=your_db sslmode=disable")
if err != nil {
    log.Fatal(err)
}
defer db.Close()

type User struct {
    ID   int    `db:"id"`
    Name string `db:"name"`
    Age  int    `db:"age"`
}

func BatchUpsertUsers(users []User) error {
    tx, err := db.Beginx()
    if err != nil {
        return err
    }
    defer tx.Rollback()

    stmt, err := tx.PrepareNamed(`
        INSERT INTO users (id, name, age)
        VALUES (:id, :name, :age)
        ON CONFLICT (id) DO UPDATE SET
            name = EXCLUDED.name,
            age = EXCLUDED.age
    `)
    if err != nil {
        return err
    }
    defer stmt.Close()

    for _, user := range users {
        _, err := stmt.Exec(user)
        if err != nil {
            return err
        }
    }

    err = tx.Commit()
    if err != nil {
        return err
    }

    return nil
}

users := []User{
    {ID: 1, Name: "Alice", Age: 25},
    {ID: 2, Name: "Bob", Age: 30},
    {ID: 3, Name: "Charlie", Age: 35},
}

err := BatchUpsertUsers(users)
if err != nil {
    log.Fatal(err)
}