What's the Best Database Design for Storing Survey Responses?

Database questionnaire design

When creating questionnaires that store answers in a database, the optimal table structure used is critical for flexibility and performance.

Two common methods are as follows:

1. Single large table:

This method involves creating a single table with columns representing each answer in the questionnaire. However, this approach can become unwieldy when the number of questions is large and can limit flexibility in changing the structure of the questionnaire.

2. Question and answer table model:

A more efficient approach is to split the questions and answers into two tables. The Questions table contains all the questionnaire questions, while the Answers table contains the individual responses linked to the respective questions.

This model has the following advantages:

• Data reusability: Pre-prepared answers can be stored in answer sheets and reused in different questionnaires.
• Flexibility: Questionnaires can be easily modified by adding or removing questions and answers without changing the existing database structure.
• Performance: Separating data into separate tables can optimize database performance by reducing the size of each table.

Extended database model:

For more complex questionnaires, the following enhanced models are recommended:

• Questionnaire form: Contains information about each questionnaire.
• Question Sheet: Lists the questions for each questionnaire, including its question type and text.
• Answer table: Stores individual questionnaire responses, each associated with a specific user and question.
• Preset Answer Sheets: Contains predefined answer options that can be reused across multiple questionnaires.
• User table: Tracks information about survey participants.

This extended model allows for greater flexibility and data reuse, as well as managing different types of questions, including text-based, multiple-choice, and multi-select options.

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