I need to write a select statement that will rewrite the table in the following manner... I'm not sure how to go about this using MySQL.
Example of table
user_id date a b c
123456 2020-01-01 1 1 1
234567 2020-03-04 1 0 0
453576 2020-05-05 1 0 1
Desired result
user_id date results
123456 2020-01-01 a
123456 2020-01-01 b
123456 2020-01-01 c
234567 2020-03-04 a
453576 2020-05-05 a
453576 2020-05-05 c
In MySQL you can unpivot with union all, while filtering on 1 values:
select user_id, date, 'a' as result from mytable where a = 1
union all select user_id, date, 'b' from mytable where b = 1
union all select user_id, date, 'c' from mytable where c = 1
order by user_id, date, result
If you have a large amount of data or your "table" is really a complex query (say a subquery or view), then unpivoting is usually faster with cross join than with union all:
select t.user_id, t.date, r.result
from t cross join
(select 'a' as result union all
select 'b' as result union all
select 'c' as result
) r
where (t.a = 1 and r.result = 'a') or
(t.b = 1 and r.result = 'b') or
(t.c = 1 and r.result = 'c') ;
For a single smallish table, performance probably doesn't matter.