1. DATA MODELING AND DATABASE DESIGN
Part 3

2. Objectives Translate Logical to Physical design
Steps for converting (mapping) Resolved ERD to set of Table Instance Charts
Table Instance Charts symbols.
Some mapping examples

3. Database Design - from Logical to Physical
Map entities and attributes to tables and columns respectively.
Naming conventions should be consistent.
Consider primary, unique and foreign keys
and check constraints as well
Additional requirements
Design the indexes
Establish view definitions
Plan the physical storage space

4. Steps to convert your Resolved ERD to TIC set
Map ENTITIES to TABLES
Map ATTRIBUTES to COLUMNS
Map * to NOT NULL constraints
Map UIDs to PRIMARY KEY constraints
Map (#) Secondary UIDs to NOT NULL and UNIQUE Constraints
Map RELATIONSHIPS to FKs

5. Table Instance Chart Symbols
PK - Primary Key
FK - Foreign Key
FK1, FK1 - Composite Foreign Keys
FK1, FK2 - Two foreign keys related to two separate tables
NN - Not Null
U - Unique
U1, U1 - Two columns unique in combination with each other
U1, U2 - Two unique (and indepenent) columns

6. Creating a TIC: Example
Create a Table Instance Chart (TIC) from the Logical Schema (Resolved ERD)
EMPLOYEE_NEW_FORCE Table
Column name
Key type
Nulls/
Unique
FK table FK
column
Datatype
Max length
Validate
emp_no
PK,FK
EMPLOYEE
NUM 7
position NN
CHAR 25
salary NN
NUM
11,2
Comm
NUM
4,2
Columns
Keys
Reference
< 10000
< 1

7. Steps for creating TIC 1: Map Entities to Tables
Create a frame for each TIC
Table name
Column names
Key types
Not Null and Unique references
Foreign key information
Column datatype and maximum length
_ Validation (Check)
Sample data
Put the table name at the top of the chart.

8. Step 2: Map the Attributes to Columns
Map each attribute from the entity to a column name in the table.
Mandatory columns get a NN constraint
Add sample data for each column (usually three rows)
Do not use SQL reserved words for column names.

9. Step 3: Map the Unique Identifiers to Primary Keys
Map the UID of the entity as the primary key in the table.
Do NOT mark it as NN and U
If there is an alternate UID, label it as NN and U,but choose only one for a PK.
Add a FK column for each UID that is through a relationship (over UID bar)

10. Step 4: Map Relationships to Foreign Keys
For One-to-Many relationships
Take the PK at the One end and create a column under same or different name in the other table at the Many end.
Mark it as a FK.
For mandatory relationships, be sure to label the NN reference.

11. Step 4: Map Relationships to Foreign Keys --- continued
For One-to-One relationships, label the U reference.
If the relationship is optional in both directions, place the FK in the table at either end of the relationship.
If the relationship is mandatory, place the unique FK in the table at the mandatory end.
For mandatory relationships, be sure to label the NN reference.

12. MAPPING: Example performed by EMPLOYEE_ ACTIVITY * per_diem_rate for
requires
performs
EMPLOYEE_NEW_FORCE
ACTIVITY
# emp_no
* position
o job_description
* salary
o commission
# activity_id
* description
o start_date
o end_date
* internal

13. Entities to tables
EMPLOYEE_NEW_FORCE
ACTIVITY
EMPLOYEE_ACTIVITY

14. Attributes to Columns ACTIVITY
Column Name id description start_date end_date internal
Key
Type
Nulls/
Uniques
FK Ref
Table
FK Column
Datatype
MAX Length
Validation

15. UID to PK and * to NOT NULL
ACTIVITY
Column Name id description start_date end_date internal
Key
Type
Nulls/
Uniques
FK Ref
Table
FK Column
Datatype
MAX Length
Validation PK NN NN

16. If Entity on Many side, then add FK Column
ACTIVITY
Column Name id description start_date end_date internal
Key
Type
Nulls/
Uniques
FK Ref
Table
FK Column
Datatype
MAX Length
Validation PK NN NN NN
We do NOT have here a FK Column !

17. Validation (Check) on Columns with Limits
ACTIVITY
Column Name id description start_date end_date internal
Key
Type
Nulls/
Uniques
FK Ref
Table
FK Column
Datatype
MAX Length
Validation PK NN NN NN
{Y,N}
>= sysdate

18. LINK - INTERSECTION ENTITIES
for
EMPLOYEE_
ACTIVITY
for

19. PK and NN EMPLOYEE_ACTIVITY
Column Name emp_no activity_id per_diem_rate
Key
Type PK PK
Nulls/
Uniques NN
FK Ref
Table
FK ref
Column
Datatype
MAX
Length

20. Foreign Keys EMPLOYEE_ACTIVITY
Column Name emp_no activity_id per_diem_rate
Key
Type PK, FK PK, FK2
Nulls/
Uniques NN
FK Ref EMPLOYEE_ ACTIVITY
table NEW_FORCE
FK ref
Column emp_no activity_id
Datatype Number Number Number
MAX
Length ,2

21. Foreign Key Mapping Rules
Map the Relationship to a foreign key.
One to One optional in both directions - take the PK from either table and make it a FK in the other table.
One to One mandatory in one direction, take the PK from the optional end and make it a FK in the entity at the mandatory end.
One to Many - Take the PK at the one end and make it a FK in the entity at the many end.
Do not forget to label mandatory relations with NN