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Editorial Team
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Asked: 2026-05-15T04:29:00+00:00

I have a table in my database that represents datafields in a custom form.

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I have a table in my database that represents datafields in a custom form. The DataField gives some representation of what kind of control it should be represented with, and what value type it should take. Simplified you can say that I have 2 entities in this table – Textbox taking any string and Textbox only taking numbers.

Now I have the different values stored in a separate table, referencing the datafield definition. What is the best way to store the data value here, when the type differs?

One possible solution is to have the FieldValue table hold one field per possible value type. Now this would certainly be redundant, but at least I would get the value stored in its correct form – simplifying queries later. 

FieldValue
----------
Id
DataFieldId
IntValue
DoubleValue
BoolValue
DataValue
..

Another possibility is just storing everything as String, and casting this in the queries. I am using .Net with NHibernate, and I see that at least here there is a Projections.Cast that can be used to cast e.g. string to int in the query.

Either way in these two solutions I need to know which type to use when doing the query, but I will know that from the DataField, so that won’t be a problem.

Anyway; I don’t think any of these solutions sounds good. Are they? Or is there a better way?

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1 Answer

  1. Editorial Team

    There is no 3rd “magic” option: your specific situation determines how you want to proceed.

    From my experience, a string-only solution makes sense with things like application settings. Usually, I don’t need to use such data in queries directly so it doesn’t bother me much that it’s in string form.

    I’m not sure, but it seems to be the case that you are extending an entity with custom attributes, which sounds like you might want to do some processing in the database at some point. In this case, you may as well go with the multiple-column approach and fill in only the column with the right type. It’s not going to be pretty, but it might simplify queries.

    As I said, it depends on if and what kind of queries you need to run, what kind of performance you need etc.

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