I am creating a database to store time entries that have been created in Clockify, I need to declare a data type for the duration field. A string is returned in the TimeIntervalDto and an example provided in the API documentation is "PT1M4S" or "PT1H30M15S". This is obviously a meaningful string if you know how to decode it. 

The example given in the API documentation is:

"timeInterval": {
 "duration": "PT1M4S", (Example: PT1H30M15S - 1 hour 30 minutes 15 seconds)
 "end": "2018-06-12T14:01:41Z",
 "start": "2018-06-12T14:00:37Z"
 },

My questions are:

1. How to I translate duration to something meaningful; and
2. What is the maximum size I would need to cater for, assuming that I'm using varchar, or nvarchar as the data type?