Awesome video but I'm pretty sure that a bridge entity whose primary key composes of the two primary keys from some other entites are actually a weak entity?
A weak entity is an entity that depends upon a strong entity to exist in the database. For example, if I have an Employee entity, and a Dependents entity, I can only have an entry in Dependents if there is a parent record in Employee. Since an employee can have more than one dependent, the PK would be PK of Employee plus another attribute, for example, Dependent_SSN. Employee is said to be the strong entity, and Dependent is the weak entity. The second part of the PK does not point to another table as a bridge entity does.
The PK of the Student table is SID, which is why it's underlined. The PK of the Teams table is TID, also underlined. PK of the bridge (or associate) entity is SID+PID. There is no foreign key in this model, those are used for 1:M relationships, not Many-to-many.
Thank you very much
Thank you, miss
I'm glad you found it helpful!
Awesome video but I'm pretty sure that a bridge entity whose primary key composes of the two primary keys from some other entites are actually a weak entity?
A weak entity is an entity that depends upon a strong entity to exist in the database. For example, if I have an Employee entity, and a Dependents entity, I can only have an entry in Dependents if there is a parent record in Employee. Since an employee can have more than one dependent, the PK would be PK of Employee plus another attribute, for example, Dependent_SSN. Employee is said to be the strong entity, and Dependent is the weak entity. The second part of the PK does not point to another table as a bridge entity does.
What is the primary and foreign key in this example?
The PK of the Student table is SID, which is why it's underlined. The PK of the Teams table is TID, also underlined. PK of the bridge (or associate) entity is SID+PID. There is no foreign key in this model, those are used for 1:M relationships, not Many-to-many.
BeSaltandLight thank you for response . I understand it. What a good way to teach. Appreciate it.
@@anilizci123 I'm not sure how you found this video, I loaded it for my students. But I'm glad that you did if it helped you!
I was working for my exam. The way our professor teach is hard to understand. I found your video on youtube search by searching☺️