function

Hi all,

how can I write function which takes text from one field, replaces
some characters and puts it in other field? I have array with old and
new values.

For example:
old array = {'r', 'Z', 'o'}
new array = {'s', 'm', 't'}
old field value = 'Zorro'
new field value which must calculate this function = 'mtsst'

This function will be used in update trigger.
Any ideas?

Normunds