How to select a table row with a random chance?

Question

SQL

There is a selection from the table:
id, chance
1, 20
2, 30,
3, 10
4, 5
chance - the chance of selecting this id.
How to do it right?
I have an idea, process in C#
Take all the data, calculate the amount of chance. Throw out a random number 0-sum. Then take one line at a time until we reach a line that is greater than the number. This is what you need
But you want something more cool.

Answer 1

Select a random number from 1 to 100
If the selected number is in the range 1-20 then the SQL query SELECT id=1
If the selected number is in the range 96-100 then the SQL query SELECT id=4
, etc.