如何在GORM中进行多个表连接

type User struct {
    ID    uint   `gorm:"primaryKey"`
    Name  string
    Posts []Post `gorm:"foreignKey:UserID"`
}

type Post struct {
    ID     uint   `gorm:"primaryKey"`
    Title  string
    UserID uint
}

var users []User
db.Preload("Posts").Find(&users)

type Result struct {
    UserID uint
    UserName string
    PostTitle string
}

var results []Result
db.Raw(`
    SELECT users.id as user_id, users.name as user_name, posts.title as post_title
    FROM users
    JOIN posts ON users.id = posts.user_id
`).Scan(&results)

var users []User
db.Joins("JOIN posts ON posts.user_id = users.id").Find(&users)

var results []struct {
    UserID   uint
    UserName string
    PostCount int
}

db.Table("users").
    Select("users.id as user_id, users.name as user_name, COUNT(posts.id) as post_count").
    Joins("LEFT JOIN posts ON posts.user_id = users.id").
    Group("users.id").
    Scan(&results)