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When / how  to use a self join?

Question asked by cgallardo on Jun 4, 2013
Latest reply on Jun 6, 2013 by cgallardo


I am playing around with a self join table. Can you please have a look at my table design and advise if I have done it properly or if you have suggestions?


This is for people sigining in and out of a building. Then if there is a fire or a fire drill, an Ipad with filemaker go is used as an attendance roll to ensure all occupants have left the building.


The database is hosted in a remote server, data is accessed via an Ipad with 3G (so if there is a disaster data can still be accessed).


Signing in and out will be done by another ipad or desktop (have not figured this out yet) secured to a wall.


I used a self join table so that I could display the data in portal. I have never used a self join before.


I created the ROLL CALL DAYS table just so I could have extra data on the layout that runs the attendance roll. I do not neet to save historical data.


My concern is that I may not be using the self join table properly. As far as the operation goes it does what is expected, but I am concerned that later if they want data to be saved it will make it difficult to change.


Should I break it in to multipletables instead? i.e. TODAY (holds the day's attendance roll), PEOPLE (holds people names and visitor/staff flag). Where would I save the time in and out, and InOut fields?


Database Design.JPG