What's the Best Database Design for Managing Survey Data?

Investigation Database Design

When designing a survey database, it is important to consider how the data is structured and organized. Here is a comprehensive analysis of both database designs, along with alternatives to solve the problems posed:

Option 1: Single table with answer column

While creating a single table with an answer column seems simple, it has some drawbacks:

• Insufficient flexibility: This structure becomes rigid, limiting changes to the survey and requiring frequent modifications to the schema.
• Data Redundancy: Answers to each question are duplicated in survey submissions, resulting in redundant data storage.

Option 2: Question table and answer table

This design involves creating separate tables for questions and answers:

• tblQuestion: Stores question information, including question ID, survey ID, question type, and question text.
• tblAnswer: Record a single answer, linking each line to a question.

While this approach provides greater flexibility, large answer tables may cause performance issues.

Improved model

To mitigate scalability issues, consider a more complex scheme of designing static (immutable) data separately from dynamic (changing) data:

• tblQuestion: Stores questions and their predefined answers.
• tblOfferedAnswer: Lists the answer options provided for each question.
• tblSurveyResponse: Record user responses, linked to specific questions and predefined answers.

This improved model has the following advantages:

• Question reusability: Predefined questions and answers can be reused across multiple surveys.
• Scalability: By storing static data in a separate table, the answer table is kept smaller and more manageable.
• Support free-text responses: The "Other" answer option allows users to provide free-text responses, thereby capturing valuable qualitative data.

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