--合格の時
update total_scores 
set
    passed = 'TRUE'
where
    total_score >=
    (
        select
            AVG(total_score)
        from
            total_scores
    );
--不合格の時
update total_scores 
set
    passed = 'FALSE'
where
    total_score <
    (
        select
            AVG(total_score)
        from
            total_scores
    );