Data validation query that compares only first 15 characters of fields in table

[DB2010MN26]

I Have two tables: OS_NAME and DS_NAME, I want to compare two fields in each table to look for differences ("NAME" field on OS_NAME, and "FT_T_ISD" on DS_NAME). I only want it to compare the first 15 characters of each field, how would I accomplish this?

[weekend00]

Following query gets names from the two tables for those names are not same but first 15 chars are same:
select os_name.name,ds_name.ds_name from os_name inner join ds_name on left(os_name.name,15)=left(ds_name.ds_name,15) where os_name.name <> ds_name.ds_name