with SubAvg as(
select avg(total_score) as avg_total
from total_scores
)

update total_scores as ts
set passed = TRUE
from SubAvg as sub
where ts.total_score >= sub.avg_total;

update total_scores as ts
set passed = FALSE
where passed = null;

----------------------------------
with SubAvg as(
select avg(total_score) as avg_total
from total_scores
)

select total_scores.*, cast(sub.avg_total as int)  from total_scores, SubAvg as sub