Application domain. Consider a simple banking application in which customers per

Question

Application domain. Consider a simple banking application in which customers perform transactions on some of their accounts. For this purpose we have the database schema that consists of the following three relation schemata: CUSTOMER Cid, name, phone ACCOUNT num, type, desc TRANSACTION num, type, cid, time, amount Domains of attributes have been omitted. The following relations constitute a database, which we denote by db. ACCOUNT CUSTOMER phone num type desc cid name cl Jack 02102205945 01 cheque expenses c2 Jill 02102205945 02 cheque expenses c3 Jill 02259682104 02 online expenses TRANSACTION num type cid time amount 01 cheque cl 24-03-14 09:32 100 01 cheque cl 24-03-14- 22:11 100 02 cheque c2 24-03-14- 22:11 100 02 online c3 24-03-14- 22:11 +100

Explanation / Answer

The cid in TRANSACTION table references cid in CUSTOMER table. Thus for every entry for cid in TRANSACTION table there should be a corresponding entry in CUSTOMER table.

Thus, first condition is satisfied.

The num,type in TRANSACTION table references num,type in ACCOUNT table and thus for each record for num,type in TRANSACTION table there should be corresponding matches in ACCOUNT table.

Thus, second condition is satisfied.

The type,num in TRANSACTION table references type,num in ACCOUNT table and thus for each record for type,num in TRANSACTION table there should be corresponding matches in ACCOUNT table.

Thus, fourth condition is satisfied.

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