HIS : How I solved it?

Id Lesson SAS R SAS Video R Video
TASKS_HIS_L1001 1- Identify the overlap of dates in exposure intervals
TASKS_HIS_L1002 2- Extract the last two characters from the values of a character variable
TASKS_HIS_L1003 3- Get the latest transfusion date on or before each lab collection date
TASKS_HIS_L1004 4- Last dosing date before an adverse event start date
TASKS_HIS_L1005 5- Check if an element start date is same as previous element end date in SE
TASKS_HIS_L1006 6- Change from previous non-missing result
TASKS_HIS_L1007 7- Filter all records of subjects with a duplicate record in ADSL
TASKS_HIS_L1008 8- Compare a table output dataset after removing spaces
TASKS_HIS_L1009 9- Check if at least one dose of a concomitant medication is taken within study treatment period