"weighting" a random select

[Anon]

So what I want to do is randomly make a selection from a database but I want to be able to weight certain entries so that they are more likely to be selected...

Does that make sense? So how is the best way to code this? I don't need examples necessarily, an abstract explanation of the algorithm would probably suffice.

Thanks!

[Anon]

My very simple solution would be to randomly pick a number from a predefined range where each each database entry would correspond to a subset of the range.

For example
Entry 1 = 1-80
Entty 2 = 81-99
Entry 3 = 99-100

then just randomly pick a number b/w 1-100 and then look-up the appropriate entry in the table above.