I guess each of us has different preferences - I have a very good experience with keeping lookup tables in the database, but as I don't fully understand your need, I hesitate to suggest a specific solution.
One thing which is not clear to me is what you write about 50 plus values. Do you mean your decision table contains 50 different parameters you use as input for calculating the result value(s), or is it a simple lookup table with a few inputs and a single output, but with 50 rows?
If you can provide a small example (even a partial one), it will be helpful.
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