How to add Embedded and Relation to room database

Let's say I have these tables :

Table - User

Stores the users

@Entity(
    tableName = "USER"
)
data class User(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "user_id")
    val id: Int,

    @ColumnInfo(name = "user_name")
    val name: String
)

Table - Item

Store the items it's like a product

@Entity(
    tableName = "ITEM"
)
data class Item(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "item_id")
    val id: Int,

    @ColumnInfo(name = "item_name")
    val name: String,

    @ColumnInfo(name = "item_description")
    val description: String
)

Table - Special

Store an speciality for product 1 Special needs a Product to exist

@Entity(
    tableName = "SPECIAL",
    foreignKeys = [ForeignKey(
        entity = Item::class,
        parentColumns = ["item_id"],
        childColumns = ["special_item_id"]
    )]
)
data class Special(
    @PrimaryKey(autoGenerate = true)
    @ColumnInfo(name = "special_id")
    val id: Int,

    @ColumnInfo(name = "special_item_id")
    val coupon_product_id: Int,

    @ColumnInfo(name = "special_name")
    val name: String,

    @ColumnInfo(name = "special_description")
    val description: String

)

Table -- Favourite

Stores the favourite Specials from an user

@Entity(
    tableName = "TB_FAVOURITE",
    foreignKeys = [ForeignKey(
        entity = User::class,
        parentColumns = ["user_id"],
        childColumns = ["favourite_user_id"]
    ), ForeignKey(
        entity = Special::class,
        parentColumns = ["special_id"],
        childColumns = ["favourite_special_id"]
    )]
)
data class Favourite(
    @PrimaryKey
    @ColumnInfo(name = "favourite_user_id")
    val id: Int,

    @ColumnInfo(name = "favourite_special_id")
    val specialId: Int

)

My question is, how can I make a query to select all the Specials and then creating like a class that stores if it's favourite of the user or not. It's one user app for the moment, it's for a demo app. So, user will always be the same so I can hardcode the findById and send the id of the user.

The goal

Is to get a result of a query as List that contains :

1. All of the Specials
2. In the SomeClass should contain the Item of the Special inside
3. A flag to know if it's favourite for that driver or not

The thing is I want to be able to map the result of the room database to my desired object, so I guess the query is more important than the mapper, I know how to do the mapper.

Note that I'm using an assets/database/mydb.db file to start the database I don't know if it matters, so I do not know how would work using Embedded and Relation here

How would be the query to do that? Is there any improvement of the structure of the db to make it easier?

from How to add Embedded and Relation to room database