Replace non-null value with column name

I am looking for a way to replace any non “?” value in a table with the column name. Can anyone suggest a good way to do this? I am looking at creating something like this (so there might be an even quicker way of doing it). My current thought is to replace all 1 with the column name and then collect together:

| ID   | Condition A | Condition B | Condition C | Combination            |
| AAA1 | 1           | 1           |             | Condition ACondition B |
| BBB2 |             | 1           |             | Condition B            |
| BBB3 |             | 1           | 1           | Condition BCondition C |

I’m falling at the first hurdle though. Thanks!