i have a dataset example below

id visit_number date value test
1 2 2020-10-01 16:00 140 sodium
79 34 2011-07-10 09:15 . xray

in these columns id is a patient unique identifier, visit_number is a visit unique identifier, data: date of visit ; test - has up to 65 different test names (coded as numbers) and value is the result of the test.

few qs:

1. i want to creat a unique identifier combining id and visit number, say A B to AB
2. how can i create new variable columns from test using the test label using a foreach loop since there are 65 different variables in that column. i have created numeric labels for each test

many thanks, hal