Patch applied or not in R12
you can get the patch applied details in EBS R12 from below command
select AP.PATCH_NAME, AP.PATCH_TYPE, AD.DRIVER_FILE_NAME, AD.CREATION_DATE, AD.PLATFORM,AL.LANGUAGE from AD_APPLIED_PATCHES AP, AD_PATCH_DRIVERS AD, AD_PATCH_DRIVER_LANGS AL where AP.APPLIED_PATCH_ID = AD.APPLIED_PATCH_ID and AD.PATCH_DRIVER_ID = AL.PATCH_DRIVER_ID and AP.PATCH_NAME='17627621'