OK - I will try another forum - I only stumbled across this one yesterday when I was trying to find a solution! Thanks everyone for their suggestions anyway.

I wondered if you could tell me why this command isn't working:

UPDATE TABLENAME SET SUBSTR(FIELDNAME,1,7) = 'XXXXXXX' WHERE SUBSTR(FIELDNAME,1,7) = 'YYYYYYY';

The error I get is:

ERROR at line 1:

ORA-00927: missing equal...