cheptsov

object Users : Table() {
    val id = varchar("id", length = 10).id() // PKColumn<String, Users>
    val name = varchar("name", length = 50) // Column<String, Users>
    val requiredCityId = integer("required_city_id").references(Cities.id) // FKColumn<Int, Users>
    val optionalCityId = integer("optional_city_id").references(Cities.id).optional() // FKOptionColumn<Int, Users>

    val all = id + name + requiredCityId + optionalCityId // Template4<Users, String, Int, Int?> Select template
    val values = id + name + requiredCityId + optionalCityId // Template4<Users, String, Int, Int?> Insert template
}

cheptsov

(Users.name + Users.cityId * Cities.name).filter { Users.id.equals("andrey") } forEach {
    val (userName, cityName) = it
    println("$userName lives in $cityName")
}

cheptsov

object Users : Table() {
   val id = varchar("id", ColumnType.PRIMARY_KEY, length = 10) // PKColumn<String>
   val name = varchar("name", length = 50) // Column<String>
   val cityId = integer("city_id", ColumnType.NULLABLE, references = Cities.id) // Column<Int?>

   val all = id + name + cityId // Column3<String, String, Int?>
}

object Cities : Table() {
   val id = integer("id", ColumnType.PRIMARY_KEY, autoIncrement = true) // PKColumn<Int>

cheptsov

object Cities : Table() {
    val id = id("id", autoIncrement = true)
    val name = varchar("name", 50)

    val all = id + name
}

select (Cities.all) forEach {
  val (id, name) = it
  println("$id: $name")

cheptsov

select (Cities.name, сount(Users.id)) from Cities join Users groupBy Cities.name forEach {
    val (cityName, userCount) = it
    if (userCount > 0) {
        println("$userCount user(s) live(s) in $cityName")
    } else {
        println("Nobody lives in $cityName")
    }
}