Just added function and group by support to the Expose SQL library for Kotlin

Select with a function and group by statement

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")
    }
}

Produces:

SQL: SELECT Cities.name, COUNT(Users.id) FROM Cities LEFT JOIN Users ON Cities.id = Users.city_id GROUP BY Cities.name

Nobody lives in Prague
1 user(s) live(s) in St. Petersburg
2 user(s) live(s) in Munich