kotlin 怎么实现多表联查呀，有没有demo,如下面两个表，我根据accid查数据时，以用户表为主表，好友关系表如果有这个id 的数据就组合数据。类似leftJoin 怎么用啊，没看到有 demo

`@WCDBTableCoding
class UserEntity {
    @WCDBField(isPrimary = true)
    var accid: String? = null
    @WCDBField
    var name: String? = null
    @WCDBField
    var avatarUrl: String? = null
}

@WCDBTableCoding
class FriendRelationEntity {
    @WCDBField(isPrimary = true)
    var id: Long = 0
    @WCDBField
    var accid: String? = null
    @WCDBField
    var alias: String? = null
}
`