Marcin,

> Let's say that I have a table containing:
> Machine_Name varchar(20)
> Config_Name varchar(20)
> Work_Date date
>
> The data for one machine may look like this:
>
> Machine_1, Config_1, 01.11.2012
> Machine_1, Config_1, 02.11.2012
> Machine_1, Config_1, 03.11.2012
> Machine_1, New_Config, 04.11.2012 <- we have set up a new configuration
> Machine_1, New_Config, 05.11.2012 Machine_1, Config_1, 06.11.2012 <-
> back to old config Machine_1, Conifg_1, 07.11.2012
>
> I'd like to create a query that returns the 'history' of configurations for one
> machine, like this:
> Config_Name, Date_From, Date_To
> Config_1, 01.11.2012, 03.11.2012
> New_Config, 04.11.2012, 05.11.2012
> Config_1, 06.11.2012, 07.11.2012
>
> Is it possible without iterating each entry for Machine_1 ?

This should do the trick:

SELECT
M.Config_name
,M.Work_Date as Date_From
,(SELECT FIRST 1 N.Work_Date FROM Table N WHERE N.Config_name = M.Config_name AND N.Work_Date < M.Work_Date ORDER BY DESC N.Work_Date) as Date To
FROM Table M
WHERE
M.Config_name = :Machine_Name


Sean