How can I shorten/fix this?

This is pretty simple, but I don't know how to do it. If I had a command block constantly running

/execute @a ~ ~ ~ /testforblock ~ ~-1 ~ minecraft:coal_block

How would I use the player that the command block just picked up in a teleportation command? Would I some how shorten/fix it like

/testfor @a[r=3]

then some teleport command instead of just using

/tp @a[r=3] (where ever)

Okay, so is there some way to put this in one single command or make it so the person the command targets actually gets remembered/tagged I guess.