I want to create a table, with each row containing some sort of weight. Then I want to select random values with the probability equal to (weight of that row)/(weight of all
The easiest (and maybe best/safest?) way to do this is to add those rows to the table as many times as you want the weight to be - say I want "Tree" to be found 2x more often then "Dog" - I insert it 2 times into the table and I insert "Dog" once and just select elements at random one by one.
If the rows are complex/big then it would be best to create a separate table (weighted_Elements or something) in which you'll just have foreign keys to the real rows inserted as many times as the weights dictate.