Have a table with about 25000 rows. Column Symbol char(6).

I would like a stored procedure that will accept a parameter that will be char(2)

If @param = 'US'

of the set of symbols beginning with U and followed by a digit - (UK not a match ) , find the max value of the digits in the string ( possible at least one of chars 2-6 will be alpha and that there may be blanks at the end

So
U290
U2888&
U2345
U00001

will get 2888

Then increment that number by 1 , padleft(5) with 0, test to see if 'U'+that string ( U02889 ) is found in the column and if not return that string
If found, increment number and try again until not match is found

If @param is char(2) ( or is not US) , do the same thing but matching against first 2 chars, then performing same procedure on remaining 4 characters.

CZ0001
CZ24&
CZ490#

returns CZ0490 if there isn't already one in the column, else CZ0491 etc until no match.

I can probably kludge up something ugly but I'm sure some of the clever TSQLers here can show me something elegant and I get to learn something.

Thanks in advance