関連ワード:  weak entity set with example    explain weak entity set with example    weak entity set in dbms with example    explain strong and weak entity set with example    define weak entity set with an example    compare strong entity set and weak entity set with example    strong and weak entity set in dbms with examples    differentiate between weak and strong entity set with example    what is weak entity set explain discriminator with example    compare strong and weak entity set with suitable example