Hi All, I have a table wich contains a set of appointments: afspraakid, day, room_number, description For example, the table is filled like this 1, wednesday, 104, drinking a cup of tea 2, thursday, 101, writing a program 3, wednesday, 104, reading a book 4, tuesday, 104, listening to music I want to automatically select all the days that a room is 'double-booked'. In my example I want MySQL to output wednesday as a day to be aware of problems because reading a book and drinking a cup of tea is scheduled in the same room wich, obviously, will lead to problems. I dont know what the SELECT-statement must look like to achieve this... Any suggestions?

There are a few different ways to do it, but the most straightforward way I could think of is something like this: select * from appts a, appts b where a.room=b.room and a.time=b.time and a.id != b.id; Make sense? -SN

Right! I didnt know, and haven't tried it because I didnt know it, that you can make a join with one table instead of two! Thank you very for the quick help! GREAT! Khalid.