Question

In a Bank’s database, there are two tables ‘Customer’ and ‘Transaction’ as shown below.

Customer

Acc_No	Cust_Name	Cust_City	Cust_Phone	Open_Bal
2101001	Sunita	Ambala	9710557614	10000
2201002	Sandhya	Patna	8223545233	15000
2301003	Vivek	New Delhi	9972136576	13000
2401004	Meena	New Delhi	9321305453	10000

Transaction

Trans_Id	Acc_No	Transaction_Type	Amount
Tr001	2301003	Credit	15000
Tr002	2201002	Credit	20000
Tr003	2101001	Debit	3500
Tr004	2301003	Credit	26000
Tr005	2301003	Credit	24000

Consider these tables while attempting the questions given below:

(i) Identify the candidate keys of Customer table.

(ii) Briefly explain the concept of Candidate keys.

(iii) Which column can be considered as foreign key column in Transaction table?

(iv) Identify Primary Key column of Transaction table.

Answer 1

(i) Acc_No, Cust_Phone

(ii) All the columns having capability to become Primary Key are known as Candidate Keys.

(iii) Acc_No

(iv) Trans_Id