Page 140 - DCAP402_DCAO204_DATABASE MANAGEMENT SYSTEM_MANAGING DATABASE

Unit 8: Normalization

Notes

Notes Partially Dependent

An attribute (column) is said to be partially dependent if its value can be determined by
any one or more attributes of the primary key, but not all.
Each normal form is built upon the previous normal form. The first statement states that the
prerequisite for second normal form is to have all its tables in first normal form.
The Fully Functional Dependency is for a given composite primary key (a primary key consisting
of more than one attribute), each column attribute, which is not an attribute of the Primary key,
should be dependent on each and every one of the primary key attributes.
If attributes dependent on only a part of the primary key attribute exist, they are removed and
placed in a separate table where the primary key of the new table is the portion of the original
key that they were dependent on.

A non-key attribute is fully functionally dependent on the primary key if it is functionally
dependent on all the attributes comprising the primary key.
A relation R is said to be in the second normal form (2NF) if and only if it is in INF and every
non-key attribute must be fully functional dependent on the Primary key.
The Customer Tran table is decomposed into three tables: Transaction, Customer Account and
Accounts.

Tables before Second Normal Form
Customer Table

Cust_id Name Address
001 Ravi Hyd
110 Tim Sec 'bad
420 Kavi Vizag

Customer_Tran Table

Tran_id Cus_id Acc_id Acc_type Min_bal Tran_type Tan_mode Amount Balance
14300 001 994 SB 1000 B/F 1000 1000
14301 001 994 SB 1000 Deposit Bycash 1000 2000
14302 001 994 SB 1000 Withdrawal ATM 500 1500
14303 110 340 CA 500 B/F 3500 3500
14304 110 340 CA 500 Deposit Payroll 3500 7000
14305 110 340 CA 500 Withdrawal ATM 1000 6000
14306 420 699 SB 1000 B/F 6000 6000
14307 420 699 SB 1000 Credit Bycash 2000 8000
14308 420 699 SB 1000 Withdrawal ATM 6500 1500

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