I guess, I found the problem after your request to post my code. The preparedStatement was created as follows:

val insertTableRow = "INSERT INTO accounts (id, name, description, birthday, salary) VALUES(?, ?, ?, ?, ?)"

val preparedInsertStatement: PreparedStatement = connection.prepareStatement(insertTableRow, Statement.RETURN_GENERATED_KEYS)

I think the "Statement.RETURN_GENERATED_KEYS" is not correct.