Hi Dr. Sun
for homework 1 questions 1

" Note that a trade may involve more than two players" in case that TRADE (ie if we take as entity set TRADE with attributes id , team name and date) is an entity set in this case then if a trade has more than one player  then playerID cant be an attribute of TRADE in this case since it doesnt qualify as a simple data type(as it is playerID (list)).. i was wondering if we can still use this entity set TRADES and  have different ids for a same trade even if a trade may involve more than two players?

Im not really clear on the above given condition? do you want each trade as one transaction?

 

professor if we were to convert this to a relational model based on the ER model should each trade have 1 transaction per trade given the fact the each trade has to have 2 teams and could have more than 2 players? each trade has one id but but how can each trade entity contain multiple players?

cysun wrote:

Each class only has one class id so how can a class contain multiple students?

so in this case players become a collection/list? does that mean there is  a need to link/create with a new relationship form from the trade entity/class to players? i think my approach to the trade entity was wrong i think i just needed to link the right entity to the right relationships thank you