Rename Photo Files Using Exif Data

Does anyone know the way (there's got to be a way) to rename photo files using the exif data, specifically the date the photo was taken. I have Irfanview, and looking around the 'net, there's some mentions of using a placeholder code, with the necessary codes, but no mention of how to apply the placeholder code in the renaming process. I need to do this as a batch process, as there's around 8000 files I'd like to rename with the date as part of the filename.

I'd be most grateful if anyone could enlighten me. TIA.