Toilet flanges provide a stable surface that the toilet grabs onto through retaining bolts.
Replace pvc toilet flange concrete floor.
Slip the repair flange spanner under the broken toilet flange but put one of the toilet bolts through the hole in the spanner first in order to easily reinstall the toilet.
When the subfloor is concrete as is often the case with basement bathrooms or other slab foundation situations replacing the flange is no easy matter since it can be quite hard to drill holes in concrete to secure the new flange.