First of all you cannot implement (without EXTREME PAIN) sha256 in a stored procedure..

With that said however, you can get an extended stored procedure that that can handle it, I found one for you at:

http://anmar.eu.org/projects/ctnhashproc/

As I see it, you create an additional column, hash the passwords into it and then delete the previous password column. Make sure that whatever you use in your apps to hash the entered password that it creates hashes that are the same, they may both be sha256 but you never know who might have screwed up..

Clear?

CEWII