select ps1.player_id, ps1.player_name, ps2.erep_day,
(ps1.sky_hero - ps2.sky_hero) as sky_heroes,
(ps1.battle_hero - ps2.battle_hero) as battle_heroes,
(ps1.player_exp - ps2.player_exp) as experience_gained,
(ps1.true_patriot - ps2.true_patriot) as true_patriots
from player_stats ps1
join player_stats ps2 on ps2.player_id = ps1.player_id and ps2.erep_day = (select max(erep_day) from player_stats) - 1
where ps1.erep_day = (select max(erep_day) from player_stats)
group by
ps1.player_id,
ps1.player_name,
ps2.erep_day,
ps1.sky_hero - ps2.sky_hero,
ps1.battle_hero - ps2.battle_hero,
ps1.player_exp - ps2.player_exp,
ps1.true_patriot - ps2.true_patriot
order by experience_gained desc;