Question

Consider the tables given below and answer the questions that follow :

Table: Event

EventId	Event	NumPerformes	CelebrityID
101	Birthday	10	C102
102	Promotion Party	20	C103
103	Engagement	12	C102
104	Wedding	15	C104

Table: Celebrity

Celebrityld	Name	Phone	FeeCharged
C101	Faiz Khan	99101956	200000
C102	Sanjay Kumar	893466448	250000
C103	Neera Khan Kapoor	981166558	300000
C104	Reena Bhatia	65877755	100000

(i) Name the Primary keys in both the tables and Foreign key in 'Event' table. Can NumPerformers (Number for performers) be set as the Primary key? Give reason.

(ii) How many rows will be present in the Cartesian join of the above mentioned two tables?

In the table 'Event', the CelebrityID 102 is present twice in the column "CelebrityId". Is there any discrepancy ? Give reason.

Answer 1

(i) Primary Key in Event: EventId

Primary Key in Celebrity: CelebrityId

Foreign Key in Event: CelebrityId

No, NumPerformers cannot be set as a Primary Key, because the number of performers can be same in multiple fields and also they have to proper patters when we talk about the teams.

(ii) 16 rows.

No, there will not be any discrepancy in the Event table because, it is not the primary key, it is only Foreign Key, whose value can appear multiple times as same.