Certain principles guide the database design process. The first principle is that duplicate information (also called redundant data) is bad, because it wastes space and increases the likelihood of errors and inconsistencies. The second principle is that the correctness and completeness of information is important. If your database contains incorrect information, any reports that pull information from the database will also contain incorrect information. As a result, any decisions you make that are based on those reports will then be misinformed.
A good database design is, therefore, one that:
- Divides your information into subject-based tables to reduce redundant data.
- Provides Access with the information it requires to join the information in the tables together as needed.
- Ensure the accuracy and integrity of your information.
- Accommodates your data processing and reporting needs.
The Database Design Process:
The design process consists of the following steps:
1. Determine the purpose of your database
This helps prepare you for the remaining steps.
2. Find and organize the information required
Gather all of the types of information you might want to record in the database, such as product name and order number.
3. Divide the information into tables
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
4. Turn information items into columns
Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example, an Employees table might include fields such as Last Name and Hire Date.
5. Specify primary keys
Choose each table’s primary key. The primary key is a column that is used to uniquely identify each row. An example might be Product ID or Order ID.
6. Set up the table relationships
Look at each table and decide how the data in one table is related to the data in other tables. Add fields to tables or create new tables to clarify the relationships, as necessary.
7. Refine your design
Analyze your design for errors. Create the tables and add a few records of sample data. See if you can get the results you want from your tables. Make adjustments to the design, as needed.
8. Apply the normalization rules
Apply the data normalization rules to see if your tables are structured correctly. Make adjustments to the tables, as needed.
A good database design is, therefore, one that:
- Divides your information into subject-based tables to reduce redundant data.
- Provides Access with the information it requires to join the information in the tables together as needed.
- Ensure the accuracy and integrity of your information.
- Accommodates your data processing and reporting needs.
The Database Design Process:
The design process consists of the following steps:
1. Determine the purpose of your database
This helps prepare you for the remaining steps.
2. Find and organize the information required
Gather all of the types of information you might want to record in the database, such as product name and order number.
3. Divide the information into tables
Divide your information items into major entities or subjects, such as Products or Orders. Each subject then becomes a table.
4. Turn information items into columns
Decide what information you want to store in each table. Each item becomes a field, and is displayed as a column in the table. For example, an Employees table might include fields such as Last Name and Hire Date.
5. Specify primary keys
Choose each table’s primary key. The primary key is a column that is used to uniquely identify each row. An example might be Product ID or Order ID.
6. Set up the table relationships
Look at each table and decide how the data in one table is related to the data in other tables. Add fields to tables or create new tables to clarify the relationships, as necessary.
7. Refine your design
Analyze your design for errors. Create the tables and add a few records of sample data. See if you can get the results you want from your tables. Make adjustments to the design, as needed.
8. Apply the normalization rules
Apply the data normalization rules to see if your tables are structured correctly. Make adjustments to the tables, as needed.
