putting concrete footer with slab
You mention a column as the footer, so I'm assuming this is a post framed type of structure with the posts sitting on concrete piers.  If so, the posts must be supported directly on the piers, not on a slab poured over the pier.  You can do this by either extending the pier to the top of the slab and using a support like this (Simpson EPB44T) with the slab poured around the pier:



Or you can bring your pier to the bottom of the slab and use this style of support (Simpson PPBZ Porch Base), which you anchor to the pier, and then pour the slab over/around it:



This is NOT engineering advice - I suggest you talk to one to properly spec out this component for your application!

(just realized this question is 5 months old and probably OBE, not sure how it ended up on my feed - hopefully you got it right)