I have slightly tweaked the `UPSERT` implementatio...

# exposed

[kushalp]

I have slightly tweaked the UPSERT implementation in one of the GitHub issues so that it returns the existing row if it's present:

fun <T : Table> T.insertOrReturn(key: Column<*>, body: T.(InsertStatement<Number>) -> Unit) =
    InsertOrReturn<Number>(this, key = key).apply {
        body(this)
        execute(TransactionManager.current())
    }

class InsertOrReturn<Key : Any>(
    table: Table,
    isIgnore: Boolean = false,
    private val key: Column<*>
) : InsertStatement<Key>(table, isIgnore) {
    override fun prepareSQL(transaction: Transaction): String {
        val tm = TransactionManager.current()
        val keyIdentity = tm.identity(key)
        val onConflict = "ON CONFLICT ($keyIdentity) DO UPDATE SET $keyIdentity = EXCLUDED.$keyIdentity"
        return "${super.prepareSQL(transaction)} $onConflict RETURNING *"
    }
}

I'm using this as follows:

val insertedCustomerRecord = Customers.insertOrReturn(Customers.uniqueId) {
    it[uniqueId] = record.uniqueId
    it[name] = record.name
    it[dateOfBirth] = record.dateOfBirth
}