Handling error in alter table or create index statement if the column / index already exists

Hi

We have a process in place where we run a script on our database that includes adding new column to an existing table or creating a new index on existing table. The script output is written to a log file

for example

Alter table test add (zipcode  varchar2(5));

OR

Create index idx_test_zip on test (zipcode)


The problem is that if the column or the index exist, we get an error

ERROR at line 1:
ORA-01430: column being added already exists in table

ERROR at line 1:
ORA-00955: name is already used by an existing object


What we need is that if the column or index to be added already exists, the script