1. ICT Database Lesson 2
Designing a Database

2. Objectives 9.2.1: Identify the components of a database.
9.2.2: Distinguish between fields and records in a database.
9.2.3: Describe the basic data types and formats used in a database.
9.2.4: Distinguish between a table and a query.
9.2.5: Identify database keys, including primary and foreign.
9.2.6: Identify the relationships between tables in a database (i.e., one- to-one, one-to-many, many-to-many).
9.2.7: Distinguish between a query and a report.
9.2.8: Identify various report types.  

3. Steps to Designing a Database
Who needs what information
Organize data tables and fields
Relate the information
Identify data types
Identify Queries, Forms and Reports

4. Fields
Specific categories of information we need to track per type of information
Variables organized as columns in a table

5. Record
A group of fields in a table related to a single entity and is contained in a row within that table

6. Primary & Foreign Key
Primary Key: uniquely identify each record in a table and help to link related records
Data contained in the primary key is unique — that is, no duplicate data can be contained in the field.
Foreign Key: a field that refers back to a primary key in another table
Will reference a unique column in another table
This primary key – foreign key relationship is how you link the tables.

7. Primary & Foreign Key Primary Key Primary Key relates to the
Foreign Key of the second table
Foreign Key

8. Table Relationships Database Table Relationship Description One-to-one
Each record in Table A can have only one matching record in Table B, and vice versa.
The relationship is created only if both of the related fields are primary keys.
One-to-many
A record in Table A can have multiple matching records in Table B, but a record in Table B has only one matching record in Table A.
The relationship is created only if the related field is the primary key in Table A and a foreign key in Table B.
Many-to-many
One record in Table A can relate to many matching records in Table B, and vice versa.

9. Table Relationships One-to-many relationship Many-to-many relationship1 8
One-to-many relationship 1 8
Many-to-many relationship

10. Junction (Join) Tables
A 3rd unique table created to join two unrelated tables
Contains the primary key fields from each of the other two tables in the relationship
Junction Table 1 8
Primary Fields
Primary Fields

11. Data Types
Text – Alphanumeric values, examples are names, and titles. This field can hold between characters.
Integer – Numeric values, such as calculations and distance. This does not include currency. There is no decimal and precision is 10 places.
Float – Numeric values that have 2 decimal points and precision up to 16 places.
Currency – Numeric values that describe money.
Date/Time – Dates and Time.
Yes/No – Boolean values, use when the only options are true or false.
Memo – Long formatted text fields more than 255 characters. A memo is the right choice for a description of an item.
Attachment – Digital media such as pictures. A record can have more than one attachment.
Hyperlink – Links to other resources such as Web sites, and addresses.
Autonumber – Provides a unique numeric value that only appears once in a table. If you delete an autonumber, that number will never appear again in that table. Many databases use an Autonumber as the primary key in record.

12. Form
Provides a simplified interface for entering, modifying, and viewing the database records