how to generate pseudo random numbers and row-count in Tableau

Question

How to generate pseudo random numbers and row-counts in Tableau? I didn't find any built-in functions (like 'RAND', 'RCOUNT').

Answer 1

Edit: Just learned that there is a Random() function in Tableau. It is not in the library but if you use it anyway, it will tell you that the formula is valid and create a value between 0 and 1.

Original and still valid answer in case you want to use officially supported functions:

Since Tableau is used to create graphs based on your data, there is usually little use for random numbers (would you explain what you need them for?)

However you could use an approach like this to work around this limitation: http://community.tableau.com/docs/DOC-1474

Basically getting a semi-random seed out of the time, combine it with other values based on table calculations and multiplying it with other semi-random values

Seed
(DATEPART('second', NOW()) + 1) * (DATEPART('minute', NOW()) + 1) * (DATEPART('hour', NOW()) + 1) * (DATEPART('day', NOW()) + 1)

Random Number
((PREVIOUS_VALUE(MIN([Seed])) * 1140671485 + 12820163) % (2^24))

Random Int
INT([Random Number] / (2^24) * [Random Upper Limit]) + 1

Where [Random Upper Limit] is a user defined value to limit the range of the result.