Sql服务器中的单元对单元的比较?

I have tbl1 :

我有tbl1:

   Id  | c1  |  c2  |  c3   |
   ____|_____|______|_______|_
    1     a     b       c 
   ____|_____|______|_______|_
    2     h     j       k
   ____|_____|______|_______|_
    3     t     y       u
   ____|_____|______|_______|_
   Id  | c1  |  c2