1. DBS201: Merging 3NF Tables
Lecture 7

2. Merging 3NF Tables
Bottom up design on a number of similar views (reports/screens) generates a series of tables in 3NF
Resulting tables are similar

3. Premiere Corporation Order Detail Report
Merging 3NF Relations
View 1
Premiere Corporation Order Detail Report
Order Order Cust Part Part Number Quoted Total
Number Date Number Number Desc Ordered Price
AX12 Iron
BT04 GasGrill
BZ66 Washer
CB03 Bike ,119.96
CX11 Blender
AZ52 Dartboard
BA74 Basketball
BT04 GasGrill
CZ81 Treadmill

4. Premiere Corporation Order Detail Report
Merging 3NF Relations
Given this view sample, working through normalization could give the following 3NF tables
Premiere Corporation Order Detail Report
Order Order Cust Part Part Number Quoted Total
Number Date Number Number Desc Ordered Price
AX12 Iron
BT04 GasGrill
BZ66 Washer
CB03 Bike ,119.96
CX11 Blender
AZ52 Dartboard
BA74 Basketball
BT04 GasGrill
CZ81 Treadmill
ORDER (ORDER_NUM(PK), ORDER_DATE, CUSTOMER_NUM)
PART (PART_NUM(PK), PART_DESC, QUOTED_PRICE)
ORDER_PART(ORDER_NUM(PK,FK), PART_NUM(PK,FK), NUM_ORDERED)

5. Merging 3NF Relations View 2 Premiere Corporation Order Detail Report
Order Order Cust Last Part Part Qty List
Number Date Number Name Number Desc Ordered Price
Adams AX12 Iron
Charles BT04 GasGrill
BZ66 Washer
Daniels CB03 Bike
Samuels CX11 Blender
Nelson AZ52 Dartboard
BA74 Basketbal
Adams BT04 GasGrill
Nelson CZ81 Treadmill

6. Merging 3NF Relations
Given this view sample, working through normalization could give the following 3NF tables
Premiere Corporation
Order Detail Report
Order Order Cust Last Part Part Qty List
Number Date Number Name Number Desc Ordered Price
Adams AX12 Iron
Charles BT04 GasGrill
BZ66 Washer
Daniels CB03 Bike
Samuels CX11 Blender
Nelson AZ52 Dartboard
BA74 Basketbal
Adams BT04 GasGrill
Nelson CZ81 Treadmill
ORDER (ORDER_NUM(PK), ORDER_DATE, CUSTOMER_NUM(FK))
CUSTOMER (CUST_NUM(PK, LAST_NAME)
PART (PART_NUM(PK), PART_DESC, LIST_PRICE)
ORDER_PART(ORDER_NUM(PK,FK), PART_NUM(PK,FK), QTY_ORDERED)

7. Merging 3NF Relations Resulting 3NF tables from both examples: View 1:
ORDER (ORDER_NUM(PK), ORDER_DATE, CUST_NUM)
PART (PART_NUM(PK), PART_DESC, QUOTED_PRICE)
ORDER_PART(ORDER_NUM(PK,FK), PART_NUM(PK,FK), NUM_ORDERED)
Notice most attributes are similarly named
Two table ‘PART’, each with a different attribute QUOTED_PRICE and LIST_PRICE. Assuming they represent the same attribute, need to give them a consistent name
ORDER (ORDER_NUM(PK), ORDER_DATE, CUST_NUM(FK))
CUSTOMER (CUST_NUM(PK, LAST_NAME)
PART (PART_NUM(PK), PART_DESC, LIST_PRICE)
ORDER_PART(ORDER_NUM(PK,FK), PART_NUM(PK,FK), QTY_ORDERED)
Notice same with QTY_ORDERED and NUM_ORDERED in the ORDER_PART tables

8. Merging 3NF Relations
Resulting Merged set of 3NF tables from both examples:
ORDER (ORDER_NUM(PK), ORDER_DATE, CUST_NUM(FK))
PART (PART_NUM(PK), PART_DESC, LIST_PRICE)
ORDER_PART(ORDER_NUM(PK,FK), PART_NUM(PK,FK), QTY_ORDERED)
CUSTOMER (CUST_NUM(PK, LAST_NAME)
Note new name in PART table: LIST_PRICE and new name in ORDER_PART table; QTY_ORDERED

9. Merging 3NF Relations Another Example - Two tables:
Step 1: Merge tables:
(Note this table is no longer in 3NF)
CUSTOMER (CUST_NUM(PK), CUST_NAME, REP_NUM)
CUSTOMER (CUST_NUM(PK), CUST_NAME, REP_LAST_NAME, REP_FIRST_NAME)
CUSTOMER (CUST_NUM(PK), CUST_NAME, REP_LAST_NAME, REP_FIRST_NAME, REP_NUM)

10. Merging 3NF Relations Normalized tables: Normalize the tables:
CUSTOMER (CUST_NUM(PK), CUST_NAME, REP_NUM, REP_FIRST_NAME, REP_LAST_NAME)
CUSTOMER (CUST_NUM(PK), CUST_NAME, REP_NUM (FK))
REP (REP_NUM(PK), REP_FIRST_NAME, REP_LAST_NAME)

11. Steps to Merge 3NF Relations
Review attribute names of 3NF relations from each user view and make them consistent across all relations
Use consistent name for relations with same attributes in primary key (i.e. CUSTOMER table and CLIENT table; both with a primary key of CUST_NUM should have the same relation name)
Examine the primary key of each relation with a composite primary key to determine if all parts should be part of the primary key (partial dependencies)
Resolve any transitive dependencies if they were created in the previous step
Revise ERD as required with one entity for each relation and a relationship for each foreign key
Revisit ERD relationships to determine what is option vs mandatory