database - Should I be storing this information as the attribute of an entity and then retrieve it? Or simply query it with instances of association? -

structure of database problem:

tv_shows     tv_show_id,      tv_show_title,      tv_show_description,      network,      status  episodes     episode_id,      tv_show_id,      episode_title,      episode_description,      air_date 

hi,

i unsure of what’s best here. output number of episodes of tv_show1, should make attribute of tv_shows table , include it? (i.e. “”no_of_episodes”) or count number of episodes there’s occurrence of id tv_show1 in episodes table query?

that’s not all...something else riddling me task. if wanted premiere date of tv_show1, make attribute in tv_shows table? or retrieve querying earliest instance of episode’s air_date?

both solutions work have no idea what's correct

the basic rule of thumb in database design: only store each piece of information in 1 place.

while system might run faster if store each count, have adjust counts each time add or remove episode. consequently, it's better count records each time query.