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copied!<p>Wheter or not to put decision tables in a database depends on a number of other questions.</p> <p>Will your conditions be calculated inside the RDBMS or elsewhere? If the data used for evaluating these conditions, and a suitable method for evaluating them inside the RDBMS can be devised, it is probably a good idea. Maybe your actions also happens inside your database, which would make it even more attractive.</p> <p>Your conditions, and even execution of your actions might be on the outside of the RDBMS, but you could still keep the connections between combinations of conditions and actions on the inside. Probably because most of you other data is there, and all you have is a web server sitting on top of it.</p> <p>I can think of two ways to model this, depending on how many conditions you have (and wheter they are binary), and what the capacity for columns per table is.</p> <p>Let's say you have 6 conditions that are binary, this means you have 2^6 = 64 possible combinations. Then you could have one column for every combination, and one row for every action.</p> <p>Or you could have 16 conditions which means you would have almost an incalculable number of combinations (actually 65536). Which is a ridiculous number of columns. Better then to have a column for each condition and a column for each action and 65536 rows of what to do in each possible situation. Each row would represent a situation and what to do in that situation. The only datatype you use would be bool. You could also package these bools into bitmasked integers.</p> <p>Actually, bigger decision tables are better avoided. Divide and rule, and use more tables is a much better way. Usually a subject matter expert will get tired if asked to give opinions on too high a number of conditions.</p> <p>The strength of the decision table is really in the modelling stage where the developer and the subject matter expert can find out if every possible situation is mapped, and no blind spots can exist.</p>

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