Query syntax

Hello,

I have an sql statement that returns data regarding patient visits. Like this:

Select pat_id, VisitDate, ….. etc from PatientData order by pat_id asc, VisitDate asc

A patient can have more than one visit so it returns data that looks like:

pat_id  visitdate,
23, 2012-03-01, …….
23, 2012-07-22, …….
23, 2014-08-03, ……
25, 2012-05-01, …….
25, 2012-09-20, …….
26, 2012-11-19, …….
26, 2013-02-22, …….
26, 2015-02-03, ……

Select allOpen in new window

Now I would like to add a flag which indicates the first visit for each patient. Like

pat_id, visitdate, firstvisit,
23, 2012-03-01, 1, …….
23, 2012-07-22, 0, …….
23, 2014-08-03, 0, ……
25, 2012-05-01, 1, …….
25, 2012-09-20, 0, …….
26, 2012-11-19, 1, …….
26, 2013-02-22, 0, …….
26, 2015-02-03, 0,……

Select allOpen in new window

I guess I need to have some sub select over each patients records but I can’t get my head round it.

Anyone who can help?