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Message Posted: Wed, 28 Oct 2009 @ 19:18:38 GMT
| Subj: | | Re: Can functions be nested in views that are used to insert |
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| From: | | Victor Sokovin |
| | Can functions be nested in views that are used to insert? I assume not and a macro would be necessary. | |
I don't think there is a common understanding of how such views could be used.
If the view uses function y=f(x), where x is a value in the table, then the INSERT should probably be done as x=f**(-1)(y), f**(-1) being the
inverse function.
The first problem is that inverse functions are not always well defined. The function you used in the example, y=UPPER(x), does not have a
single-value inverse function. It maps 'a' and 'A' to 'A'.
Now, you can get away in your example by applying the same y=f(x) for INSERT, because UPPER() has the property that f(f(x))=f(x) but that's a
rather exceptional property. If y=x**2, then f(f(x))=x**4, i.e., the view users will see the fourth power of x.
Perhaps it would be interesting to be able to store a transformation in some database object and use it for INSERTS but regular views don't
seem to be good candidates for this.
Victor
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