Question

In reference to this question, I am facing almost the same scenario except that in my case, the questions are probably static (it’s subject to change from time to time, and I still think it’s not a good idea adding columns for each question, but even I decided to add, how should the answers be specified/retrieved from), but the answers are in different types, for examples the answer could be yes/no, list-items, free text, list-items OR free text (Other, Please specify), multiple-selectable-list items etc.

What would be an efficient way to implement this?

Answer 1

Shimmy, I have written a four-part article that addresses this issue – see Creating a Dynamic, Data-Drive User Interface. The article looks at how to let a user define what data to store about clients, so it’s not an exact examination of your question, but it’s pretty close. Namely, my article shows how to let an end user define the type of data to store, which is along the lines of what you want.

The following ER diagram gives the gist of the data model:

Here, DynamicAttributesForClients is the table that indicates what user-created attributes a user wants to track for his clients. In short, each attribute has a DataTypeId value, which indicates whether it’s a Boolean attribute, a Text attribute, a Numeric attribute, and so on. In your case, this table would store the questions of the survey.

The DynamicValuesForClients table holds the values stored for a particular client for a particular attribute. In your case, this table would store the answers to the questions of the survey. The actual value is stored in the DynamicValue column, which is of type sql_variant, allowing any type of data – numeric, bit, string, etc. – to be stored there.

My article does not address how to handle multiple-choice questions, where a user may select one option from a preset list of options, but enhancing the data model to allow this is pretty straightforward. You would create a new table named DynamicListOptions with the following columns:

• DynamicListOptionId – a primary key
• DynamicAttributeId – specifies what attribute these questions are associated with
• OptionText – the option text

So if you had an attribute that was a multiple-choice option you’d populate the drop-down list in the user interface with the options returned from the query:

SELECT OptionText
FROM DynamicListOptions
WHERE DynamicAttributeId = ...

Finally, you would store the selected DynamicListOptionId value in the DynamicValuesForClients.DynamicValue column to record the list option they selected (or use NULL if they did not choose an item).

Give the article a read through. There is a complete, working demo you can download, which includes the complete database and its model. Also, the four articles that make up the series explore the data model in depth and show how to build a web-based (ASP.NET) user interface for letting users define dynamic attributes, how to display them for data entry, and so forth.

Happy Programming!