Type-safe database table declaration using Kotlin language and Expose library

gistfile1.kt

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>
   val name = varchar("name", 50) // Column<String>

   val all = id + name // Column2<Int, String>
}

fun main(args: Array) {
var db = Database("jdbc:h2:mem:test", driver = "org.h2.Driver")
db.withSession {
create (Cities, Users)
}
}

Generates:

CREATE TABLE Cities (id INT PRIMARY KEY AUTO_INCREMENT NOT NULL, name VARCHAR(50) NOT NULL)
CREATE TABLE Users (id VARCHAR(10) PRIMARY KEY NOT NULL, name VARCHAR(50) NOT NULL, city_id INT NULL)

See https://github.com/cheptsov/Exposed for more details