Replace Nth occurence of a string

[Vlad]

I need to replace the second occurrence of one string within another:-

E.g.

'Shoppingtrolley,Shoppingbasket'

needs to be come

'Shoppingtrolley,Emptybasket'

Any ideas?

TIA

[Michael Moore]

SELECT SUBSTR (mystr, 1, INSTR (mystr, ',')) || 'Emptybasket'

  FROM (SELECT 'Shoppingtrolley,Shoppingbasket' mystr

          FROM DUAL);

[Vlad]

Cheers Michael ;-)