Hello!

This is Babar, quite new here in this forum and here is my first question.
" I have a long data of patients who who were admitted to hospital for cardiovascular diseases and I want to check that, were they were using cardiovascular disease before the admission or not. And I also have a purchase history of medicines on different dates. I want to check that how many used it before admission and how many not? Could kindly guide me how can I count such people. Here is an example of my data.

Person 1: 05jan2010 (admission date) 14jan 2010 (discharge date)

Purchase history: 05 Dec 06 (1st purchase) 02 Feb 07 (second purchase) 05jul07 (3rd purchase) etc.

Thank you in advance.