Do we create an Index?

Hi All,

Have a question about Indexes.

We have a ZTable and we would like to create secondary indexes on the table.

Lets say the table has 5 fields a,b,c,d,e with a and b being primary keys.

Now we have a Select query as

select b from ztable where c in p_c and d in p_d.

Right now we already have a secondary index on fileds in the order b,c,d

However in our case we are not specifying b in the where clause.

Does it help creating a new index on fileds c,d, or would it be a replica of the existing index.

Any inputs will be appreciated.

Regards

Brain