Re: Survey with many columns

Em Fri, 15 Aug 2003 18:16:14 +0200, Philipp Lenssen escreveu:

> working on a project which should store data from a long
> survey. His single table now has many, many columns (labelled "a_1_1"
> and so on), with different data types (some boolean, some integers, some
> text, and so on).
>
> Is there a way to optimize this?

        Presumably the survey is a consolidation of assorted information about many different entities. One should determine the entities, model the database and normalise it. One will probably end up with many different relations, and no NULLs -- probably special values, but no NULLs.

> E.g. what would be if the next survey comes along, one which has
> different fields.

        Depends.

        If one insists on treating the survey as one entity, the next different survey is obviously another entity, and thus another relation.

        If one has modeled the database according to perceived entities and normalised it, the next survey will be a simple addition of the new entities and attributes, as new relations and perhaps new attributes in old relations. One might even come to create views to preserve the old logical model without using neither NULLs nor default values without a meaning...

        Suggestion: grok the relational model by reading Date.

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