ok here's a quick prototype i *think* does what you are asking;

it's basically a power-replace that cross joins your funciton symbols with a know list of repalces;

does this work the way you expect?

with MyTable(ID,SomeString)

AS

(

SELECT 1,'L@*K@*H@/324' UNION ALL

SELECT 2,'(AF#-AR#)*(Y#+BB#)' UNION ALL

SELECT 3,'TT#*(L#+D@)*C@' UNION ALL

SELECT 4,'((AE#-AR#)*(Y#+A#))/Y#/'

),

MyFn (fnval) AS

(

SELECT '@' UNION ALL

SELECT '&' UNION ALL

SELECT '#'

),

MyReplaceMents (oldval,newval)

AS

(

SELECT 'L','AT'

)

select

MyTable.* ,

REPLACE(SomeString,oldval + MyFn.fnval ,newval + MyFn.fnval ) AS NEWVAL

FROM MyTable

CROSS JOIN MyFn

CROSS JOIN MyReplaceMents