how to get specific data from the cloud

So i see there is a CloudGet('field','variable');

I have two questions

1. is there a way to get data from the cloud by using one field as the identifier and then displaying the other field. basic example, in the datacloud you have a name and pin variable. you add your name (bob) and pin (1234) to the database. so lets say i want to say if name = bob then show pin or show pin for bob.

2. in this link i have two slides, slide one allows me to send name and pin to the database. slide two gets the data from the cloud and displays it. how do the database make sure it is sending back the correct data. let us say if 3 people did this process at the same time, would the database know who is who?