Excel 2007 : Need to combine duplicates into one single value

Hello,

I'm new to Excel and to this forum, so I will ask for your patience. I looked for a thread to help me with this problem, but have so far been unable to find one.

I have a list of patients who have been admitted to the hospital during a certain period of time (about 10 years). There are over 12,000 entries. Every patient is identified by his personal record number. The first column indicates the ID number, the second the religion, the third the age, the fourth the gender, the 5th the length of stay, the 6th the diagnosis, the 7th the severity score of their disease and the 8th whether they died or not. There are several patients who were admitted more than once, sometimes with a different diagnosis. If a patient with ID number of 1234, for example, was admitted three times, he will appear once with a length of stay of, let's say, 3 days, then another time for 5 days and then another time for 8 days.

How can I combine the entries for this patient so that it appears once and with a length of stay that is the sum of all his admissions ( 3+5+8=16 days). I would probably have to do this in a simplified version of the table without the diagnosis (since they may be different at each time) and probably without the age, the severity score and death since they can also be different, I don't know.

Anybody has an idea?

Thanks

PS: I have Excel 2007 (I have to correct my profile)