Alternative for MAX operator on bit fields

问题

I have table with permissions that has few bit fields. I want to group rows in this table and get result with top permissions. So with this table:

UserId, Permisssion1,Permission2, Permisssion3 

With this to rows
13,1,0,0
13,0,1,0

I want to get:
13,1,1,0

Problem is that operator MAX doesn't works on bit fields. How to do that in efficient way? (without using CASE)

回答1:

As simple as...

MAX(CAST(Permisssion1 AS tinyint))

You don't have many other options...

来源：https://stackoverflow.com/questions/9077263/alternative-for-max-operator-on-bit-fields