Generating random strings with T-SQL

Question

If you wanted to generate a pseudorandom alphanumeric string using T-SQL, how would you do it? How would you exclude characters like dollar signs, dashes, and slashes from

Answer 1

Similar to the first example, but with more flexibility:

-- min_length = 8, max_length = 12
SET @Length = RAND() * 5 + 8
-- SET @Length = RAND() * (max_length - min_length + 1) + min_length

-- define allowable character explicitly - easy to read this way an easy to 
-- omit easily confused chars like l (ell) and 1 (one) or 0 (zero) and O (oh)
SET @CharPool = 
    'abcdefghijkmnopqrstuvwxyzABCDEFGHIJKLMNPQRSTUVWXYZ23456789.,-_!$@#%^&*'
SET @PoolLength = Len(@CharPool)

SET @LoopCount = 0
SET @RandomString = ''

WHILE (@LoopCount < @Length) BEGIN
    SELECT @RandomString = @RandomString + 
        SUBSTRING(@Charpool, CONVERT(int, RAND() * @PoolLength), 1)
    SELECT @LoopCount = @LoopCount + 1
END

I forgot to mention one of the other features that makes this more flexible. By repeating blocks of characters in @CharPool, you can increase the weighting on certain characters so that they are more likely to be chosen.